Differential acoustic touch and force sensing

ABSTRACT

Acoustic touch and/or force sensing system architectures and methods for acoustic touch and/or force sensing can be used to detect a position of an object touching a surface and an amount of force applied to the surface by the object. The position and/or an applied force can be determined using time-of-flight (TOF) techniques, for example. Acoustic touch sensing can utilize transducers (e.g., piezoelectric) to simultaneously transmit ultrasonic waves along a surface and through a thickness of a deformable material. The location of the object and the applied force can be determined based on the amount of time elapsing between the transmission of the waves and receipt of the reflected waves. In some examples, an acoustic touch sensing system can be insensitive to water contact on the device surface, and thus acoustic touch sensing can be used for touch sensing in devices that may become wet or fully submerged in water.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/988,991, filed May 24, 2018, published as U.S. Publication Number2018-0341347 on Nov. 29, 2018, which claims priority to U.S. ProvisionalApplication Ser. No. 62/510,493, filed May 24, 2017, U.S. ProvisionalApplication Ser. No. 62/510,513, filed May 24, 2017, U.S. ProvisionalApplication Ser. No. 62/561,578, filed Sep. 21, 2017 and U.S.Provisional Application Ser. No. 62/561,609, filed Sep. 21, 2017, thecontents of which are hereby incorporated herein by reference in theirentirety for all purposes.

FIELD OF THE DISCLOSURE

This relates generally to touch and/or force sensing systems, and moreparticularly, to integrated acoustic touch and force sensing systems andmethods for acoustic touch and force sensing.

BACKGROUND OF THE DISCLOSURE

Many types of input devices are presently available for performingoperations in a computing system, such as buttons or keys, mice,trackballs, joysticks, touch sensor panels, touch screens and the like.Touch screens, in particular, are becoming increasingly popular becauseof their ease and versatility of operation as well as their decliningprice. Touch screens can include a touch sensor panel, which can be aclear panel with a touch-sensitive surface, and a display device such asa liquid crystal display (LCD) that can be positioned partially or fullybehind the panel so that the touch-sensitive surface can cover at leasta portion of the viewable area of the display device. Touch screens canallow a user to perform various functions by touching the touch sensorpanel using a finger, stylus or other object at a location oftendictated by a user interface (UI) being displayed by the display device.In general, touch screens can recognize a touch and the position of thetouch on the touch sensor panel, and the computing system can theninterpret the touch in accordance with the display appearing at the timeof the touch, and thereafter can perform one or more actions based onthe touch. In the case of some touch sensing systems, a physical touchon the display is not needed to detect a touch. For example, in somecapacitive-type touch sensing systems, fringing electrical fields usedto detect touch can extend beyond the surface of the display, andobjects approaching near the surface may be detected near the surfacewithout actually touching the surface. Capacitive-type touch sensingsystems, however, can experience reduced performance due to conductive,electrically-floating objects (e.g., water droplets) in contact with thetouch-sensitive surface.

SUMMARY

This relates to acoustic touch and/or force sensing systems and methodsfor acoustic touch and/or force sensing. The position of an objecttouching a surface can be determined using time-of-flight (TOF)techniques, for example. Acoustic touch and/or force sensing can utilizetransducers, such as piezoelectric transducers, to transmit ultrasonicwaves along a surface and/or through the thickness of one or morematerials (e.g., a thickness of an electronic device housing). As thewave propagates along the surface and/or through the thickness of theone or more materials, an object (e.g., finger, stylus, etc.) in contactwith the surface can interact with the transmitted wave, causing areflection of at least a portion of the transmitted wave. Portions ofthe transmitted wave energy after interaction with the object can bemeasured to determine the touch location of the object on the surface ofthe device. For example, one or more transducers (e.g., acoustictransducers) coupled to a surface of a device can be configured totransmit an acoustic wave along the surface and/or through the thicknessof the one or more materials and can receive a portion of the wavereflected back when the acoustic wave encounters a finger or otherobject touching the surface. The location of the object can bedetermined, for example, based on the amount of time elapsing betweenthe transmission of the wave and the detection of the reflected wave.Acoustic touch sensing can be used instead of, or in conjunction with,other touch sensing techniques, such as resistive, optical, and/orcapacitive touch sensing. In some examples, the acoustic touch sensingtechniques described herein can be used on a metal housing surface of adevice, which may be unsuitable for capacitive or resistive touchsensing due to interference (e.g., of the housing with the capacitive orresistive sensors housed in the metal housing). In some examples, theacoustic touch sensing techniques described herein can be used on aglass surface of a display or touch screen. In some examples, anacoustic touch sensing system can be configured to be insensitive tocontact on the device surface by water, and thus acoustic touch sensingcan be used for touch sensing in devices that may become wet or fullysubmerged in water.

Additionally or alternatively, a force applied by the object on thesurface can also be determined using TOF techniques. For example, one ormore transducers can transmit ultrasonic waves through the thickness ofa deformable material, and reflected waves from the opposite edge of thedeformable material can be measured to determine a TOF or a change inTOF. The TOF, or change in TOF (ATOF), can correspond to the thicknessof the deformable material (or changes in thickness) due to forceapplied to the surface. Thus, the TOF or change in TOF (or the thicknessor change in thickness) can be used to determine the applied force. Insome examples, using acoustic touch and force sensing can reduce thecomplexity of the touch and force sensing system by reducing the sensinghardware requirements (e.g., transducers, sensing circuitry/controllers,etc. can be integrated/shared).

The present disclosure is primarily directed to timing and switchingschemes for acoustic touch sensing as described with regard to FIGS.19A-36B below. FIGS. 1A-18C provide context to the timing and switchingschemes as well as several exemplary configurations illustrating touchand force sensing systems according to examples of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1E illustrate exemplary systems with touch screens that caninclude acoustic sensors for detecting contact between an object and asurface of the system according to examples of the disclosure.

FIG. 2 illustrates an exemplary block diagram of an electronic deviceincluding an acoustic touch and/or force sensing system according toexamples of the disclosure.

FIG. 3A illustrates an exemplary process for acoustic touch and/or forcesensing of an object in contact with a touch and/or force sensitivesurface according to examples of the disclosure.

FIG. 3B illustrates an exemplary system, which can perform an exemplaryprocess for acoustic touch and/or force sensing of an object in contactwith a touch and/or force sensitive surface, according to examples ofthe disclosure.

FIG. 3C illustrates a transducer without pixelated electrodes accordingto examples of the disclosure.

FIG. 4 illustrates an exemplary configuration of an acoustic touchand/or force sensing circuit according to examples of the disclosure.

FIGS. 5A-5C illustrate exemplary system configurations and timingdiagrams for acoustic touch sensing to determine position usingtime-of-flight measurements according to examples of the disclosure.

FIGS. 6A-6D illustrate exemplary system configurations and timingdiagrams for acoustic force sensing to determine an amount of appliedforce using a time-of-flight measurement according to examples of thedisclosure.

FIG. 7 illustrates a timing diagram for acoustic touch and force sensingaccording to examples of the disclosure.

FIGS. 8A-8C illustrate an exemplary cover glass ringing effect andexemplary mitigations for the ringing effect according to examples ofthe disclosure.

FIG. 9A illustrates a representation of spatial and temporaldistribution of energy received by a transducer due to the ringingeffect described in FIG. 8A.

FIG. 9B illustrates a representation of spatial and temporaldistribution of energy received by a transducer during a touch sensingoperation.

FIG. 9C illustrates a spatial differential electrode configuration fortransducer electrodes alongside the spatial and temporal distribution ofenergy due to the ringing effect according to examples of thedisclosure.

FIG. 9D illustrates the spatial differential electrode configuration fortransducer electrodes alongside the representation of spatial andtemporal distribution of energy of a touch sensing signal according toexamples of the disclosure.

FIGS. 10A-10B illustrate exemplary spatial differential force sensingconfigurations according to examples of the disclosure.

FIGS. 11A-11E illustrate electrode arrangement grouping patterns forsingle-sided spatial differential electrode configurations according toexamples of the disclosure.

FIG. 12A illustrates an exemplary configuration for a spatialdifferential electrode configuration having differential electrodes onboth sides of a transducer according to examples of the disclosure.

FIG. 12B illustrates an exemplary connection pattern for performingacoustic wave transmission, touch measurement, and force measurements.

FIGS. 13A and 13B illustrated exemplary configurations and groupings fordouble sided differential electrode configurations according to examplesof the disclosure.

FIGS. 14A-14F illustrate exemplary amplifier configurations forperforming differential sensing according to examples of the disclosure.

FIGS. 15A-15C illustrate a spatial null phenomenon that can beassociated with spatial differential electrode configurations accordingto examples of the disclosure.

FIGS. 16A-16D illustrate an exemplary quadrature spatial differentialelectrode configuration according to examples of the disclosure.

FIGS. 17A-17C illustrates a first exemplary spatial electrodeconfiguration for performing quadrature spatial differentialmeasurements of touch signals on cover glass and force sensing using ashared set of electrodes according to examples of the disclosure.

FIGS. 18A-18C illustrates a second exemplary spatial electrodeconfiguration for performing quadrature spatial differentialmeasurements of touch signals on cover glass and force sensing using ashared set of electrodes according to examples of the disclosure.

FIGS. 19A-20B illustrate exemplary timing diagrams for acoustic touchand force sensing according to examples of the disclosure.

FIGS. 21-27 illustrate exemplary switching configurations for acoustictouch and force sensing systems according to examples of the disclosure.

FIGS. 28A-30B illustrate exemplary timing diagrams for acoustic touchand force sensing according to examples of the disclosure.

FIGS. 31A-34 illustrate exemplary switching configurations forquadrature acoustic touch and force sensing systems according toexamples of the disclosure.

FIGS. 35A-36B illustrate exemplary transmitter configurations foracoustic touch and force sensing systems according to examples of thedisclosure.

FIGS. 37A-37Q illustrate exemplary transducers according to examples ofthe disclosure.

DETAILED DESCRIPTION

In the following description of various examples, reference is made tothe accompanying drawings which form a part hereof, and in which it isshown by way of illustration specific examples that can be practiced. Itis to be understood that other examples can be used and structuralchanges can be made without departing from the scope of the variousexamples.

This relates to acoustic touch and/or force sensing systems and methodsfor acoustic touch and/or force sensing. The position of an objecttouching a surface can be determined using time-of-flight (TOF)techniques, for example. Acoustic touch and/or force sensing can utilizetransducers, such as piezoelectric transducers, to transmit ultrasonicwaves along a surface and/or through the thickness of one or morematerials (e.g., a thickness of an electronic device housing). As thewave propagates along the surface and/or through the thickness of theone or more materials, an object (e.g., finger, stylus, etc.) in contactwith the surface can interact with the transmitted wave, causing areflection of at least a portion of the transmitted wave. Portions ofthe transmitted wave energy after interaction with the object can bemeasured to determine the touch location of the object on the surface ofthe device. For example, one or more transducers (e.g., acoustictransducers) coupled to a surface of a device can be configured totransmit an acoustic wave along the surface and/or through the thicknessof the one or more materials and can receive a portion of the wavereflected back when the acoustic wave encounters a finger or otherobject touching the surface. The location of the object can bedetermined, for example, based on the amount of time elapsing betweenthe transmission of the wave and the detection of the reflected wave.Acoustic touch sensing can be used instead of, or in conjunction with,other touch sensing techniques, such as resistive, optical, and/orcapacitive touch sensing. In some examples, the acoustic touch sensingtechniques described herein can be used on a metal housing surface of adevice, which may be unsuitable for capacitive or resistive touchsensing due to interference (e.g., of the housing with the capacitive orresistive sensors housed in the metal housing). In some examples, theacoustic touch sensing techniques described herein can be used on aglass surface of a display or touch screen. In some examples, anacoustic touch sensing system can be configured to be insensitive tocontact on the device surface by water, and thus acoustic touch sensingcan be used for touch sensing in devices that may become wet or fullysubmerged in water.

Additionally or alternatively, a force applied by the object on thesurface can also be determined using TOF techniques. For example, one ormore transducers can transmit ultrasonic waves through the thickness ofa deformable material, and reflected waves from the opposite edge of thedeformable material can be measured to determine a TOF or a change inTOF. The TOF, or change in TOF (ATOF), can correspond to the thicknessof the deformable material (or changes in thickness) due to forceapplied to the surface. Thus, the TOF or change in TOF (or the thicknessor change in thickness) can be used to determine the applied force. Insome examples, using acoustic touch and force sensing can reduce thecomplexity of the touch and force sensing system by reducing the sensinghardware requirements (e.g., transducers, sensing circuitry/controllers,etc. can be integrated/shared).

The present disclosure is primarily directed to timing and switchingschemes for acoustic touch sensing as described with regard to FIGS.19A-36B below. FIGS. 1A-18C provide context to the timing and switchingschemes as well as several exemplary configurations illustrating touchand force sensing systems according to examples of the disclosure.

FIGS. 1A-1E illustrate exemplary systems with touch screens that caninclude acoustic sensors for detecting contact between an object (e.g.,a finger or stylus) and a surface of the system according to examples ofthe disclosure. Detecting contact can include detecting a location ofcontact and/or an amount of force applied to a touch-sensitive surface.FIG. 1A illustrates an exemplary mobile telephone 136 that includes atouch screen 124 and can include an acoustic touch and/or force sensingsystem according to examples of the disclosure. FIG. 1B illustrates anexample digital media player 140 that includes a touch screen 126 andcan include an acoustic touch and/or force sensing system according toexamples of the disclosure. FIG. 1C illustrates an example personalcomputer 144 that includes a touch screen 128 and a track pad 146, andcan include an acoustic touch and/or force sensing system according toexamples of the disclosure. FIG. 1D illustrates an example tabletcomputing device 148 that includes a touch screen 130 and can include anacoustic touch and/or force sensing system according to examples of thedisclosure. FIG. 1E illustrates an example wearable device 150 (e.g., awatch) that includes a touch screen 152 and can include an acoustictouch and/or force sensing system according to examples of thedisclosure. Wearable device 150 can be coupled to a user via strap 154or any other suitable fastener. It should be understood that the exampledevices illustrated in FIGS. 1A-1E are provided by way of example, andother types of devices can include an acoustic touch and/or forcesensing system for detecting contact between an object and a surface ofthe device. Additionally, although the devices illustrated in FIGS.1A-1E include touch screens, in some examples, the devices may have anon-touch-sensitive display.

Acoustic sensors can be incorporated in the above described systems toadd acoustic touch and/or force sensing capabilities to a surface of thesystem. For example, in some examples, a touch screen (e.g., capacitive,resistive, etc.) can be augmented with acoustic sensors to provide atouch and/or force sensing capability for use in wet environments orunder conditions where the device may get wet (e.g., exercise, swimming,rain, washing hands). In some examples, an otherwise non-touch sensitivedisplay screen can be augmented with acoustic sensors to provide a touchand/or force sensing capability. In such examples, a touch screen can beimplemented without the stack-up required for a capacitive touch screen.In some examples, the acoustic sensors can be used to provide touchand/or force sensing capability for a non-display surface. For example,the acoustic sensors can be used to provide touch sensing capabilitiesfor a track pad 146, a button, a scroll wheel, part or all of thehousing or any other surfaces of the device (e.g., on the front, rear orsides).

FIG. 2 illustrates an exemplary block diagram of an electronic deviceincluding an acoustic touch and/or force sensing system according toexamples of the disclosure. In some examples, housing 202 of device 200(e.g., corresponding to devices 136, 140, 144, 148, and 150 above) canbe coupled (e.g., mechanically) with one or more acoustic transducers204. In some examples, transducers 204 can be piezoelectric transducers,which can be made to vibrate by the application of electrical signalswhen acting as a transmitter, and generate electrical signals based ondetected vibrations when acting as a receiver. In some examples,transducers 204 can be formed from a piezoelectric ceramic material(e.g., PZT or KNN) or a piezoelectric plastic material (e.g., PVDF orPLLA). Similarly, transducers 204 can produce electrical energy as anoutput when vibrated. In some examples, transducers 204 can be bonded tohousing 202 by a bonding agent (e.g., a thin layer of stiff epoxy). Insome examples, transducers 204 can be deposited on one or more surfaces(e.g., a cover glass of touch screen 208 and/or a deformable material asdescribed in more detail below) through processes such as deposition,lithography, or the like. In some examples, transducers 204 can bebonded to the one or more surfaces using electrically conductive ornon-conductive bonding materials. When electrical energy is applied totransducers 204 it can cause the transducers to vibrate, the one or moresurfaces in contact with the transducers can also be caused to vibrate,and the vibrations of the molecules of the surface material canpropagate as an acoustic wave through the one or moresurfaces/materials. In some examples, vibration of transducers 204 canbe used to produce ultrasonic acoustic waves at a selected frequencyover a broad frequency range (e.g., 500 kHz-10 MHz) in the medium of thesurface of the electronic device which can be metal, plastic, glass,wood, or the like. It should be understood that other frequenciesoutside of the exemplary range above can be used while remaining withinthe scope of the present disclosure.

In some examples, transducers 204 can be partially or completelydisposed on (or coupled to) a portion of a touch screen 208. Forexample, touch screen 208 (e.g., capacitive) may include a glass panel(cover glass) or a plastic cover, and a display region of the touchscreen may be surrounded by a non-display region (e.g., a black borderregion surrounding the periphery of the display region of touch screen208). In some examples, transducers 204 can be disposed partially orcompletely in the black mask region of touch screen 208 (e.g., on theback side of the glass panel behind the black mask) such that thetransducers are not visible (or are only partially visible) to a user.In some examples, transducers 204 can be partially or completelydisposed on (or coupled to) a portion of a deformable material (notshown). In some examples, the deformable material can be disposedbetween touch screen 208 and a rigid material (e.g., a portion ofhousing 202). In some examples, the deformable material can be silicone,rubber or polyethylene. In some examples, the deformable material canalso be used for water sealing of the device.

Device 200 can further include acoustic touch and/or force sensingcircuitry 206, which can include circuitry for driving electricalsignals to stimulate vibration of transducers 204 (e.g., transmitcircuitry), as well as circuitry for sensing electrical signals outputby transducers 204 when the transducer is stimulated by receivedacoustic energy (e.g., receive circuitry). In some examples, timingoperations for acoustic touch and/or force sensing circuitry 206 canoptionally be provided by a separate acoustic touch and/or force sensingcontroller 210 that can control timing of and other operations byacoustic touch and/or force sensing circuitry 206. In some examples,touch and/or force sensing controller 210 can be coupled betweenacoustic touch and/or force sensing circuitry 206 and host processor214. In some examples, controller functions can be integrated withacoustic touch and/or force sensing circuitry 206 (e.g., on a singleintegrated circuit). In particular, examples integrating touch and forcesensing circuitry and controller functionality into a single integratedcircuit can reduce the number of transducers (sensor elements) andelectronic chipsets for a touch and force sensing device. Output datafrom acoustic touch and/or force sensing circuitry 206 can be output toa host processor 214 for further processing to determine a location ofand a force applied by an object contacting the device as will bedescribed in more detail below. In some examples, the processing fordetermining the location of and a force applied by the contacting objectcan be performed by acoustic touch and/or force sensing circuitry 206,acoustic touch and/or force sensing controller 210 or a separatesub-processor of device 200 (not shown).

In addition to acoustic touch and/or force sensing, device 200 caninclude additional touch circuitry 212 and optionally a touch controller(not shown) that can be coupled to the touch screen 208. In examplesincluding a touch controller, the touch controller can be disposedbetween touch circuitry 212 and host processor 214. Touch circuitry 212can, for example, be capacitive or resistive touch sensing circuitry,and can be used to detect contact and/or hovering of objects (e.g.,fingers, styli) in contact with and/or in proximity to touch screen 208,particularly in the display region of the touch screen. Thus, device 200can include multiple types of sensing circuitry (e.g., touch circuitry212 and acoustic touch and/or force sensing circuitry 206) for detectingobjects (and their positions and/or applied force) in different regionsof the device and/or for different purposes, as will be described inmore detail below. Although described herein as including a touchscreen, it should be understood that touch circuitry 212 can be omitted,and in some examples, touch screen 208 can be replaced by an otherwisenon-touch-sensitive display (e.g., but-for the acoustic sensors).

Host processor 214 can receive acoustic or other touch outputs (e.g.,capacitive) and/or force outputs and perform actions based on the touchoutputs and/or force outputs. Host processor 214 can also be connectedto program storage 216 and touch screen 208. Host processor 214 can, forexample, communicate with touch screen 208 to generate an image on touchscreen 208, such as an image of a user interface (UI), and can use touchsensing circuitry 212 and/or acoustic touch and/or force sensingcircuitry 206 (and, in some examples, their respective controllers) todetect a touch on or near touch screen 208 and/or an applied force, suchas a touch input and/or force input to the displayed UI. The touch inputand/or force input can be used by computer programs stored in programstorage 216 to perform actions that can include, but are not limited to,moving an object such as a cursor or pointer, scrolling or panning,adjusting control settings, opening a file or document, viewing a menu,making a selection, executing instructions, operating a peripheraldevice connected to the host device, answering a telephone call, placinga telephone call, terminating a telephone call, changing the volume oraudio settings, storing information related to telephone communicationssuch as addresses, frequently dialed numbers, received calls, missedcalls, logging onto a computer or a computer network, permittingauthorized individuals access to restricted areas of the computer orcomputer network, loading a user profile associated with a user'spreferred arrangement of the computer desktop, permitting access to webcontent, launching a particular program, encrypting or decoding amessage, and/or the like. Host processor 214 can also perform additionalfunctions that may not be related to touch and/or force processing.

Note that one or more of the functions described herein can be performedby firmware stored in memory and executed by touch circuitry 212 and/oracoustic touch and/or force sensing circuitry 206 (or their respectivecontrollers), or stored in program storage 216 and executed by hostprocessor 214. The firmware can also be stored and/or transported withinany non-transitory computer-readable storage medium for use by or inconnection with an instruction execution system, apparatus, or device,such as a computer-based system, processor-containing system, or othersystem that can fetch the instructions from the instruction executionsystem, apparatus, or device and execute the instructions. In thecontext of this document, a “non-transitory computer-readable storagemedium” can be any medium (excluding a signal) that can contain or storethe program for use by or in connection with the instruction executionsystem, apparatus, or device. The non-transitory computer readablemedium storage can include, but is not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus or device, a portable computer diskette (magnetic), a randomaccess memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), anerasable programmable read-only memory (EPROM) (magnetic), a portableoptical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flashmemory such as compact flash cards, secured digital cards, USB memorydevices, memory sticks, and the like.

The firmware can also be propagated within any transport medium for useby or in connection with an instruction execution system, apparatus, ordevice, such as a computer-based system, processor-containing system, orother system that can fetch the instructions from the instructionexecution system, apparatus, or device and execute the instructions. Inthe context of this document, a “transport medium” can be any mediumthat can communicate, propagate or transport the program for use by orin connection with the instruction execution system, apparatus, ordevice. The transport readable medium can include, but is not limitedto, an electronic, magnetic, optical, electromagnetic or infrared wiredor wireless propagation medium.

It is to be understood that device 200 is not limited to the componentsand configuration of FIG. 2, but can include other or additionalcomponents in multiple configurations according to various examples.Additionally, the components of device 200 can be included within asingle device, or can be distributed between multiple devices.Additionally, it should be understood that the connections between thecomponents is exemplary and different unidirectional or bidirectionalconnections can be included between the components depending on theimplementation, irrespective of the arrows shown in the configuration ofFIG. 2.

FIG. 3A illustrates an exemplary process 300 for acoustic touch and/orforce sensing of an object in contact with a touch and/or forcesensitive surface according to examples of the disclosure. FIG. 3Billustrates an exemplary system 310, which can perform an exemplaryprocess 300 for acoustic touch and/or force sensing of an object incontact with a touch and/or force sensitive surface, according toexamples of the disclosure. At 302, acoustic energy can be transmitted(e.g., by one or more transducers 204) along a surface and/or throughthe thickness of a material in the form of an ultrasonic wave, forexample. For example, as illustrated in FIG. 3B, transducer 314 cangenerate a transmit ultrasonic wave 322 in cover glass 312 (or othermaterial capable of propagating an ultrasonic wave). In some examples,the wave can propagate as a compressive wave, a guided wave such as ashear horizontal wave, a Rayleigh wave, a Lamb wave, a Love wave, aStoneley wave, or a surface acoustic wave. Other propagation modes forthe transmitted acoustic energy can also exist based on the propertiesof the surface material, geometry and the manner of energy transmissionfrom the transducers to the surface of the device. In some examples, thesurface can be formed from glass, plastic, or sapphire crystal (e.g.,touch screen 208, cover glass 312) or the surface can be formed frommetal, ceramics, plastic, or wood (e.g., housing 202). Transmittedenergy can propagate along the surface (e.g., cover glass 312) and/orthrough the thickness until a discontinuity in the surface is reached(e.g., an object, such as a finger 320, in contact with the surface),which can cause a portion of the energy to reflect. In some examples, adiscontinuity can occur at edges (e.g., edge 330) of the surfacematerial (e.g., when the ultrasonic wave propagates to the edge of thesurface opposite the transducer). When the transmitted energy reachesone of the discontinuities described above, some of the energy can bereflected, and a portion of the reflected energy (e.g., object-reflectedwave 326, edge-reflected wave 328) can be directed to one or moretransducers (e.g., transducers 204, 314). In some examples, water orother fluids in contact with the surface of the device (e.g., device200) will not act as a discontinuity to the acoustic waves, and thus theacoustic touch sensing process can be effective for detecting thepresence of an object (e.g., a user's finger) even in the presence ofwater drops (or other low-viscosity fluids) on the surface of the deviceor even while the device is fully submerged.

At 304, returning acoustic energy can be received, and the acousticenergy can be converted to an electrical signal by one or moretransducers (e.g., transducers 204). For example, as illustrated in FIG.3B, object-reflected wave 326 and edge-reflected wave 328 can bereceived by transducer 314 and converted into an electrical signal.

At 306, the acoustic sensing system can determine whether one or moreobjects is contacting the surface of the device, and can further detectthe position of one or more objects based on the received acousticenergy. In some examples, a distance of the object from the transmissionsource (e.g., transducers 204) can be determined from a time-of-flightbetween transmission and reception of reflected energy, and apropagation rate of the ultrasonic wave through the material. In someexamples, baseline reflected energy from one or more intentionallyincluded discontinuities (e.g., edges) can be compared to a measuredvalue of reflected energy corresponding to the one or morediscontinuities. The baseline reflected energy can be determined duringa measurement when no object (e.g., finger) is in contact with thesurface. Deviations of the reflected energy from the baseline can becorrelated with a presence of an object touching the surface.

Although process 300, as described above, generally refers to reflectedwaves received by the same transducer(s) that transmitted the waves, insome examples, the transmitter and receiver functions can be separatedsuch that the transmission of acoustic energy at 302 and receivingacoustic energy at 304 may occur at different co-located transducers(e.g., one transducer in a transmit configuration and one transducer ina receive configuration). In some examples, the acoustic energy can betransmitted along and/or through the surface (e.g., cover glass 312) byone or more transducers (e.g., transducer 314) and received on anopposite edge (e.g., edge 330) of the surface by one or more additionaltransducers (not shown). The attenuation of the received acoustic energycan be used to detect the presence of and/or identify the position ofone or more objects (e.g., finger 320) on the surface (e.g., cover glass312). Exemplary device configurations and measurement timing examplesthat can be used to implement process 300 will be described in furtherdetail below. In some examples, the transmitted acoustic energy fromtransducer 314 can be received at the transmitting transducer and alsoreceived at one or more other non-transmitting transducers located indifferent positions (e.g., at different edges of the surface (e.g.,cover glass 312). Energy can reflect from one or more objects atmultiple angles, and the energy received at all of the receivingtransducers can be used to determine the position of the one or moreobjects. In some examples, the non-transmitting transducers can be freeof artifacts that can be associated with transmitting acoustic energy(e.g., ringing).

In some examples, the acoustic energy transmitted and received through adeformable material can be used to determine changes in the thickness ofthe deformable material and/or an applied force. For example, at 302,acoustic energy can be transmitted (e.g., by transducer 314) through thethickness of deformable material 316 in the form of a transmitultrasonic wave 324. Transmitted energy can propagate through thedeformable material 316 until it reaches a discontinuity at the rigidmaterial 318 (e.g., at the opposite edge of the deformable material316). When the transmitted energy reaches the discontinuity, some of theenergy can be reflected, and a portion of the reflected energy can bedirected back to transducer 314. At 304, returning acoustic energy canbe received, and the acoustic energy can be converted to an electricalsignal by transducers 314. At 306, the acoustic sensing system candetermine an amount of force applied by one or more objects contactingthe surface (e.g., cover glass 312) based on the received acousticenergy. In some examples, a thickness of deformable material 316 can bedetermined from a time-of-flight between transmission and reception ofreflected energy, and a propagation rate of the ultrasonic wave throughthe material. Changes in the thickness of the deformable material (orthe time-of-flight through the deformable material) can be used todetermine an amount of applied force, as described in more detail below.

FIG. 4 illustrates an exemplary configuration of an acoustic touchand/or force sensing circuit 400 according to examples of thedisclosure. Acoustic touch and/or force sensing circuit 400 can includetransmit circuitry (also referred to herein as Tx circuitry ortransmitter) 402, switching circuitry 404, receive circuitry (alsoreferred to herein as Rx circuitry or receiver) 408 and input/output(I/O) circuit 420 (which together can correspond to acoustic touchand/or force sensing circuitry 206) and acoustic scan control logic 422(which can correspond to acoustic touch and/or force sensing controller210). Transmitter 402, switching circuitry 404, receiver 408, I/Ocircuit 420 and/or acoustic scan control logic 422 can be implemented inan application specific integrated circuit (ASIC) in some examples. Insome examples, acoustic touch and/or force sensing circuit 400 can alsooptionally include transducers 406 (which can correspond to transducers204).

In some examples, a transmitter 402 can generate an electrical signalfor stimulating movement of one or more of a plurality of transducers406. In some examples, the transmitted signal can be a differentialsignal, and in some examples, the transmitted signal can be asingle-ended signal. In some examples, transmitter 402 can be a simplebuffer, and the transmitted signal can be a pulse (or burst of pulses ata particular frequency). In some examples, transmitter 402 can include adigital-to-analog converter (DAC) 402A and an optional filter 402B thatcan be optionally used to smooth a quantized output of DAC 402A. In someexamples, characteristics of the transducer itself can provide afiltering property and filter 402B can be omitted. DAC 402A can be usedto generate transmit waveform (e.g., any transmit waveform suitable forthe touch and/or force sensing operations discussed herein). In someexamples, the transmit waveform output can be pre-distorted to equalizethe channel. In some examples, the characteristics of each channel, suchas the properties of the surface material (and/or deformable material)coupled to transducers 406, the discontinuities in the surface materialand/or deformable material, and the reflection characteristics of anedge of the device or deformable material can be measured and stored. Insome examples, the channel characteristics can be measured as amanufacturing step (or factory calibration step), and in other examplesthe characteristics can be measured as a periodic calibration step(i.e., once a month, once a year, etc. depending on how quickly thechannel characteristics are expected to change). In some examples, thechannel characteristics can be converted to a transfer function of thechannel, and the transmit waveform can be configured using the inverseof the channel transfer function such that the returning signal isequalized (e.g., returning signal can be detected as a pulse or a burstof pulses despite the transmitted waveform having a seemingly arbitrarywaveform). In some examples, a single differential pulse can be used asa transmit waveform. For example, a bipolar square pulse (where thevoltage applied to the transducer can be both positive and negative) canbe used as the transmit waveform, and the bipolar square pulse can beimplemented using a single-ended or differential implementation.

Switching circuitry 404 can include multiplexers (MUXs) and/ordemultiplexers (DEMUXs) that can be used to selectively coupletransmitter 402 and/or receiver 408 to one of transducers 406 that canbe the active transducer for a particular measurement step in ameasurement cycle. In a differential implementation, switching circuitry404 can include two MUXs and two DEMUXs. In some examples, a DEMUX canhave a ground connection, and the non-selected DEMUX outputs can beshorted, open, or grounded. In some examples, the same transducer 406can be coupled to transmitter 402 by switching circuitry 404 (e.g.,DEMUXs) during the drive mode and coupled to receiver 408 by switchingcircuitry 404 (e.g., MUXs) during the receive mode. Thus, in someexamples, a single transducer 406 can be used both for transmitting andreceiving acoustic energy. In some examples, a first transducer can becoupled to transmitter 402 by switching circuitry 404 (e.g. DEMUXs) anda second transducer can be coupled by switching circuitry 404 (e.g.,MUXs) to receiver 408. For example, the transmitting transducer and thereceiving transducer can be discrete piezoelectric elements, where thetransmitting transducer can be designed for being driven by highervoltages (or currents) to produce sufficient motion in transducer 406 togenerate an acoustic wave in the surface of a device (e.g., device 200above), and the receiving transducer can be designed for receivingsmaller amplitude reflected energy. In such a configuration, thetransmit-side circuitry (e.g., transmitter 402 and DEMUXs of switchingcircuitry 404) can be optionally implemented on a high voltage circuit,and the receive-side circuitry (e.g., receiver 408 and MUXs of switchingcircuitry 404) can be optionally implemented on a separate low voltagecircuit. In some examples, switching circuitry 404 (MUXs and DEMUXs) canalso be implemented on the high voltage circuit to properly isolate theremaining receive-side circuitry (e.g., receiver 408) duringtransmission operations by transmit side circuitry. Additionally oralternatively, in some examples, the transmit circuit can include anenergy recovery architecture that can be used to recover some of theenergy required for charging and discharging the transducer. It shouldbe understood that for a single-ended implementation, switchingcircuitry 404 can include a single DEMUX and MUX. In such aconfiguration, transmitter 402 and receiver 408 can be single-ended aswell. Differential implementations, however, can provide improved noisesuppression over a single-ended implementation.

Receiver 408 can include an amplifier 410 such as a low-noise amplifier(LNA) configured to sense the transducer. Receiver 408 can also includea gain and offset correction circuit 412. The gain and offset correctioncircuit can include a programmable gain amplifier (PGA) configured toapply gain to increase (or in some cases decrease) the amplitude of thesignals received from LNA. The PGA can also be configured to filter(e.g., low pass) the signals received from the LNA to remove highfrequency components. Additionally, the PGA circuit can also beconfigured to perform baselining (offset correction).

In some examples, the output of gain and offset correction circuit 412can optionally be coupled to one or more analog processing circuits. Insome examples, the output of gain and offset correction circuit 412 canbe coupled to a demodulation circuit 414 configured to demodulate thereceived signals (e.g., by I/Q demodulation). In some examples, theoutput of the gain and offset correction circuit 412 can be coupled toan envelope detection circuit 415 configured to perform envelopedetection on the received signals. In some examples, the output of gainand offset correction circuit 412 can be filtered at filter 416. In someexamples, these blocks/circuits can be placed in a different order. Insome examples, the processing of one or more of these analog processingcircuits can be performed in the digital domain.

The received signals, whether raw or processed by one or more ofdemodulation circuit 414, envelope detection circuit 415 or filter 416,can be passed to an analog-to-digital converter (ADC) 418 for conversionto a digital signal. In some examples, an input/output (I/O) circuit 420can be used to transmit received data for processing. In some examples,the output of I/O circuit 420 can be transferred to a host processor ofthe device, or to an auxiliary processor (sub-processor) separate fromthe host processor. For example, as illustrated, the output of I/Ocircuit 420 can be coupled to a processor system-on-chip (SoC) 430,which can include one or more processors. In some examples, processorSoC 430 can include a host processor 432 (e.g., an active modeprocessor) and an auxiliary processor 434 (e.g., a low power processor).In some examples, some digital signal processing can be performed (e.g.,by acoustic touch and/or force sensing circuit 400) before transmittingthe data to other processors in the system (e.g., processor SoC 430). Insome examples, the I/O circuit 420 is not only used for data transfer toprocessor SoC 430 (e.g., host processor 432), but also is used forwriting the control registers and/or firmware download from processorSoC 430.

The components of receiver circuitry 408 described above can beimplemented to detect touch (e.g., presence and location of a touch on asurface). In some examples, receiver 408 can also include a forcedetection circuit 424 to detect applied force (e.g., of the touch on thesurface). In some examples, the force detection circuit 424 can includethe same or similar components as described above (e.g., amplifier, gainand offset correction, etc.). In some examples, the function of forcedetection circuit 424 can be performed using the same componentsdescribed above that are used to determine time-of-flight for touchdetection. In some examples, a low-power time gating circuit can be usedto determine time-of-flight for force detection. Data from force sensingcircuit 424 can be transferred to I/O circuit 420 and/or processor SoC430 for further processing of force data in a similar manner asdescribed above for touch data. In some examples the same circuitry fortouch detection can be used to detect force.

A control circuit, acoustic scan control circuit 422, can be used tocontrol timing and operations of the circuitry of acoustic touch and/orforce sensing circuit 400. Acoustic scan control circuit 422 can beimplemented in hardware, firmware, software or a combination thereof. Insome examples, acoustic scan control circuit 422 can include digitallogic and timing control. Digital logic can provide the variouscomponents of acoustic touch and/or sensing circuit 400 with controlsignals. A timing control circuit can generate timing signals foracoustic touch and/or sensing circuit 400 and generally sequence theoperations of acoustic touch and/or force sensing circuit 400. In someexamples, the acoustic touch and/or force sensing circuit 400 canreceive a master clock signal from an external source (e.g., clock fromthe host processor, crystal oscillator, ring oscillator, RC oscillator,or other high-performance oscillator). In some examples, an on-chiposcillator can be used to generate the clock. In some examples, a masterclock signal can be generated by an on-chip phase locked loop (PLL),included as part of acoustic touch and/or force sensing circuit 400,using an external clock as the input. In some examples, a master clocksignal can be routed to the acoustic touch sensing circuit fromprocessor SoC 430. The appropriate master clock source can be determinedbased on a tradeoff between area, thickness of the stack-up, power andelectromagnetic interference.

It is to be understood that the configuration of FIG. 4 is not limitedto the components and configuration of FIG. 4, but can include other oradditional components (e.g., memory, signal processor, etc.) in multipleconfigurations according to various examples. Additionally, some or allof the components illustrated in FIG. 4 can be included in a singlecircuit, or can be divided among multiple circuits while remainingwithin the scope of the examples of the disclosure.

As described herein, various acoustic sensing techniques can be used todetermine the position of an object touching a surface and/or itsapplied force on the surface. In some examples, one or moretime-of-flight measurements can be performed using one or more acoustictransducers to determine boundaries of the position of the contactingobject. FIGS. 5A-5C illustrate exemplary system configurations andtiming diagrams for acoustic touch sensing to determine position usingtime-of-flight measurements according to examples of the disclosure.FIG. 5A illustrates an exemplary acoustic touch sensing systemconfiguration using four acoustic transducers 502A-D mounted along (orotherwise coupled to) four edges of a surface 500 (e.g., correspondingto cover glass 312). Transducers 502A-D can be configured to generateacoustic waves (e.g., shear horizontal waves) and to receive thereflected acoustic waves. Propagation of shear horizontal waves can beunaffected by water on surface 500 because low viscosity fluids andgases (such as water and air) have a very low shear modulus, andtherefore do not perturb the boundary conditions that affect wavepropagation. Shear horizontal waves can be highly directional waves suchthat the active detection region (or active area) 504 can be effectivelydefined based on the position and dimensions of the acoustic transducers502A-D. It should be understood, however, that active area can changebased on the directionality property of the acoustic waves and the sizeand placement of acoustic transducers 502A-D. Additionally, it should beunderstood that although illustrated as transmit and receive transducers(i.e., transceivers), in some examples, the transmit and receivefunctions can be divided (e.g., between two transducers in proximity toone another, rather than one transmit and receive transducer).

The position of a touch 506 from an object in contact with surface 500can be determined by calculating TOF measurements in a measurement cycleusing each of acoustic transducers 502A-D. For example, in a firstmeasurement step of the measurement cycle, acoustic transducer 502A cantransmit an acoustic wave and receive reflections from the acousticwave. When no object is present, the received reflection can be thereflection from the acoustic wave reaching the opposite edge of surface500. However, when an object is touching surface 500 (e.g.,corresponding to touch 506), a reflection corresponding to the objectcan be received before receiving the reflection from the opposite edge.Based on the received reflection corresponding to the object received attransducer 502A, the system can determine a distance to the edge (e.g.,leading edge) of touch 506, marked by boundary line 510A. Similarmeasurements can be performed by transducers 502B, 502C and 502D todetermine a distance to the remaining edges of touch 506, indicated byboundary lines 510B, 510C and 510D. Taken together, the measureddistances as represented by boundary lines 510A-510D can form a boundingbox 508. In some examples, based on the bounding box, the acoustic touchsensing system can determine the area of the touch (e.g., the area ofthe bounding box). Based on the bounding box, the acoustic touch sensingsystem can determine position of touch 506 (e.g., based on a centroidand/or area of the bounding box).

The acoustic touch sensing scan described with reference to FIG. 5A cancorrespond to the acoustic touch detection described above withreference to FIGS. 3A and 3B. Acoustic waves transmitted and receivedalong or through cover glass 312 can be used to determine theposition/location of an object touching the surface of cover glass 312.

FIG. 5B illustrates an exemplary timing diagram 560 for an acoustictouch sensing scan described in FIG. 5A according to examples of thedisclosure. As illustrated in FIG. 5B, each of the transducers cantransmit acoustic waves and then receive reflected waves in a series ofmeasurement steps. For example, from t0 to t1 a first transducer (e.g.,acoustic transducer 502A) can be stimulated, and reflections at thefirst transducer can be received from t1 to t2. From t2 to t3 a secondtransducer (e.g., acoustic transducer 502B) can be stimulated, andreflections at the second transducer can be received from t3 to t4. Fromt4 to t5 a third transducer (e.g., acoustic transducer 502C) can bestimulated, and reflections at the third transducer can be received fromt5 to t6. From t6 to t7 a fourth transducer (e.g., acoustic transducer502D) can be stimulated, and reflections at the fourth transducer can bereceived from t7 to t8. Although the transmit (Tx) and receive (Rx)functions are shown back-to-back in FIG. 5B for each transducer, in someexamples, gaps can be included between Tx and Rx functions for atransducer (e.g., to minimize capturing portions of the transmitted waveat the receiver), and or between the Tx/Rx functions of two differenttransducers (such that acoustic energy and the transients caused bymultiple reflections from a scan by one transducer does not impact ascan by a second transducer). In some examples, unused transducers canbe grounded (e.g., by multiplexers/demultiplexers in switching circuitry404).

The distance between an object touching the surface and a transducer canbe calculated based on TOF principles. The acoustic energy received bytransducers can be used to determine a timing parameter indicative of aleading edge of a touch. The propagation rate of the acoustic wavethrough the material forming the surface can be a known relationshipbetween distance and time. Taken together, the known relationshipbetween distance and time and the timing parameter can be used todetermine distance. FIG. 5C illustrates an exemplary timing diagramaccording to examples of the disclosure. FIG. 5C illustrates thetransducer energy output versus time. Signal 550 can correspond to theacoustic energy at the transducer from the generation of the acousticwave at a first edge of the surface. Signal 552 can correspond to theacoustic energy at the transducer received from the wave reflected offof a second edge opposite the first edge of the surface. Due to theknown distance across the surface from the first edge to the oppositesecond edge and the known or measured propagation rate of the acousticsignal, the reflection off of the opposite edge of the surface occurs ata known time. Additionally, one or more objects (e.g., fingers) touchingthe surface can cause reflections of energy in the time between thegeneration of the wave and the edge reflection (i.e., between signals550 and 552). For example, signals 554 and 556 can correspond toreflections of two objects touching the surface (or a leading andtrailing edge of one object). It should be understood that signals550-556 are exemplary and the actual shape of the energy received can bedifferent in practice.

In some examples, the timing parameter can be a moment in time that canbe derived from the reflected energy. For example, the time can refer tothat time at which a threshold amplitude of a packet of the reflectedenergy is detected. In some examples, rather than a threshold amplitude,a threshold energy of the packet of reflected energy can be detected,and the time can refer to that time at which a threshold energy of thepacket is detected. The threshold amplitude or threshold energy canindicate the leading edge of the object in contact with the surface. Insome examples, the timing parameter can be a time range rather than apoint in time. To improve the resolution of a TOF-based sensing scheme,the frequency of the ultrasonic wave and sampling rate of the receiverscan be increased (e.g., so that receipt of the reflected wave can belocalized to a narrower peak that can be more accurately correlated witha moment in time).

In some examples (e.g., as illustrated in FIG. 5B), transducers 502A-Dcan operate in a time multiplexed manner, such that each transducertransmits and receives an acoustic wave at a different time during ameasurement cycle so that the waves from one transducer do not interferewith waves from another transducer. In other examples, the transducerscan operate in parallel or partially in parallel in time. The signalsfrom the respective transducers can then be distinguished based ondifferent characteristics of the signals (e.g., different frequencies,phases and/or amplitudes).

Although four transducers are illustrated in FIG. 5A, in some examples,fewer transducers can be used. For example, when using an input objectwith known dimensions (e.g., stylus or a size-characterized finger ortarget), as few as two transducers mounted along two perpendicular edgescan be used. Based on the known dimensions of an object, a bounding box518 can be formed by adding the known dimensions of the object to thefirst and second distances, for example. Additionally, although FIG. 5Aillustrates detection of a single object (e.g., single touch), in someexamples, the acoustic touch sensing system can use more transducers andbe configured to detect multiple touches (e.g., by replacing each oftransducers 502A-D with multiple smaller transducers).

TOF schemes described with reference to FIGS. 5A-5C can provide fortouch sensing capability using a limited number of transducers (e.g., ascompared with a number of electrodes/touch nodes of a capacitive touchsensing system) which can simplify the transmitting and receivingelectronics, and can reduce time and memory requirements for processing.Although FIGS. 5A-5C discuss using a bounding box based on TOFmeasurements to determine position of an object, in other examples,different methods can be used, including applying matched filtering to aknown transmitted ultrasonic pulse shape, and using a center of masscalculation on the filtered output (e.g., instead of a centroid).

In some examples, a time-of-flight measurement can be performed usingone or more acoustic transducers to determine an amount of force appliedby an object touching a surface. FIGS. 6A-6D illustrate exemplary systemconfigurations and timing diagrams for acoustic force sensing todetermine an amount of applied force using a time-of-flight measurementaccording to examples of the disclosure. FIG. 6A illustrates anexemplary acoustic force sensing system stack-up 600 including adeformable material 604 in between two rigid surfaces. One of the rigidsurfaces can be a cover glass 601 (e.g., corresponding to cover glass312). The second of the rigid surfaces can be a portion of a devicehousing, for example (e.g., corresponding to housing 202). An acoustictransducer 602 (e.g., corresponding to transducer 314) can mounted to(or otherwise coupled to) the deformable material 604. For example, asillustrated in FIG. 6A, transducer 602 can be disposed between coverglass 601 and deformable material 604. Transducer 602 can be configuredto generate acoustic waves (e.g., shear horizontal waves) and to receivethe reflected acoustic waves from the discontinuity at the edge betweendeformable material 604 and rigid material 606. It should be understoodthat although illustrated as transmit and receive transducers (i.e.,transceivers), in some examples, the transmit and receive functions canbe divided (e.g., between two transducers in proximity to one another,rather than one transmit and receive transducer). Shear horizontal wavescan be highly directional waves such that the time of flight can beeffectively measure the thickness of the deformable material. A baselinethickness (or time-of-flight) can be determined for a no-forcecondition, such that changes in thickness (Δd) (or time-of-flight) canbe measured. Changes in thickness or time-of-flight can correspond toamount of applied force.

For example, plot 630 of FIG. 6D illustrates an exemplary relationshipbetween time-of-flight (or thickness) and applied force according toexamples of the disclosure. For example, in a steady state condition,where there is no change in time-of-flight across the deformablematerial 604, the applied force can be zero. As the time-of flightvaries (e.g., decreases), the applied force can vary as well (e.g.,increase). Plot 630 illustrates a linear relationship between TOF andforce, but in some examples, the relationship can be non-linear. Therelationship between TOF and applied force can be empirically determined(e.g., at calibration) using a correlation. In some examples, thecalibration can include linearizing the inferred applied force andnormalizing the measurements (e.g., removing gain and offset errors). Insome examples, the Young's modulus of the deformable material can beselected below a threshold to allow a small applied force to introduce adetectable normal deformation.

FIG. 6B illustrates another exemplary acoustic force sensing systemstack-up 610 including a deformable material 614 in between two rigidsurfaces (e.g., between cover glass 611 and rigid material 618). Anacoustic transducer 612 can mounted to (or otherwise coupled to) oneside of deformable material 614, and a second acoustic transducer 616can be mounted to (or otherwise coupled to) a second side (opposite thefirst side) of deformable material 614. For example, as illustrated inFIG. 6B, transducer 612 can be disposed between cover glass 611 anddeformable material 614 and transducer 616 can be disposed between rigidmaterial 618 and deformable material 614. Transducer 612 can beconfigured to generate acoustic waves (e.g., shear horizontal waves) andtransducer 616 can be configured to receive the acoustic waves. Theconfiguration of transducers in stack-up 610 can be referred to as a“pitch-catch” configuration in which one transducer on one side of amaterial transmits acoustic waves to a second transducer on an oppositeside, rather than relying on a reflected acoustic wave. Thetime-of-flight between the time of transmission and the time of receiptof the acoustic wave can be measured to determine the amount of appliedforce in a similar manner as discussed above with respect to FIG. 6D.

FIG. 6C illustrates an exemplary timing diagram 640 according toexamples of the disclosure. FIG. 6C illustrates the transducer energyoutput versus time. Signal 620 can correspond to the acoustic energy attransducer 602 from the generation of the acoustic wave at a first edgeof the deformable material 604. Signal 622 can correspond to theacoustic energy at transducer 602 received from a first wave reflectedoff of a second edge, opposite the first edge, of the deformablematerial 604. Due to the known distance across the surface from thefirst edge to the opposite, second edge (under steady-state) and theknown or measured propagation rate of the acoustic signal, thereflection off of the opposite edge of the surface occurs at a knowntime. In some examples, rather than using the first reflection, adifferent reflection of the acoustic energy can be used to determinetime of flight. For example, signal 624 can refer to the acoustic energyat transducer 602 received from a second wave reflected off of thesecond edge of deformable material 604 (e.g., signal 622 can reflect offof the first side of 604 deformable material and reflect a second timeoff of the second edge of deformable material 604). In some examples,signal 626 can correspond to an integer number reflection after repeatedreflections between the two edges of deformable material 604. It shouldbe understood that signals 620-626 are exemplary and the actual shape ofthe energy received can be different in practice. In some examples, thechoice of which reflection to use for the time-of-flight calculation forforce sensing can be a function of the thickness of the material and thefrequency of the transmitted wave.

In some examples, rather than using time-of-flight measurements todetermine thickness of the deformable material, other methods can beused. For example, transducer 602 can stimulate the deformable material604 with ultrasonic waves at a resonant frequency. As the deformablematerial 604 changes in thickness due to applied force, the resonantfrequency can shift. The change in resonant frequency can be measured todetermine the applied force. Using a resonant frequency can result inbetter signal-to-noise ratio (SNR) performance and better accuracy ascompared with the time-of-flight method.

As described above with reference to FIGS. 3A-3B, in some examplesacoustic touch and force sensing can both be performed. In someexamples, the two operations can be time-multiplexed. Transducers 502A-D(e.g., one of which can correspond to transducer 314) can generatetransmit waveforms and receive reflections to determine alocation/position of touch on a surface (e.g., cover glass 312) asdescribed with reference to timing diagram 560 during an acoustic touchsensing phase. Transducer 602 (e.g., corresponding to transducer 314)can generate a transmit waveform and receive a reflection to determinean amount of force applied to the surface (e.g., cover glass 312) asdescribed with reference to timing diagram 640 during an acoustic forcesensing phase.

In some examples, the acoustic touch and force sensing can be performedusing transmit waveforms generated at the same time. FIG. 7 illustratesa timing diagram 700 for acoustic touch and force sensing according toexamples of the disclosure. Signal 702 can correspond to a transmitwaveform generated by a transducer (e.g., transducer 314) tosimultaneously propagate in deformable material 316 and in cover glass312. Signal 704 can correspond to a reflection (e.g., a firstreflection) from the boundary between deformable material 316 and rigidmaterial 318. Signal 706 can correspond to a reflection from an object(e.g., a finger) on the surface of cover glass 312. Signal 708 cancorrespond to a reflection from the opposite edge of cover glass 312.Based on the timing of signal 704, the acoustic touch and force sensingcircuitry can measure a time-of-flight across the deformable material.Based on the timing of signals 706 and/or 708, the acoustic touch andforce sensing circuitry can measure the time-of-flight along the surfaceof cover glass 312 to an object (or an edge when no object is contactingthe cover glass). The time-of-flight measurements for touch can berepeated for each transducer 502A-D (e.g., four times) to determine thelocation/position of the object. The time-of-flight measurements canoptionally be repeated (e.g., for each of transducers 502A-D) to measureforce applied to the cover glass 312. In some examples, an average forcemeasurement can be determined from repeated force measurements. In someexamples, the repeated measurements can indicate relative force appliedto different edges of the cover glass. In some examples, themeasurements and different edges of the cover glass can be combined todetermine an applied force.

Performing acoustic touch and force sensing using one or more sharedtransducers can provide for both touch and force information with oneset of ultrasonic transducers (e.g., 502A-D) and one sensing circuit(e.g., acoustic touch and/or force sensing circuit 400). As a result,the touch and force sensing systems can potentially be reduced in size,in complexity and in power consumption.

Performance of ultrasonic touch and force sensing using ultrasonic wavestransmitted into deformable material 316 and cover glass 312 at the sametime can depend, in some examples, on the separation between thetransmitted ultrasonic waves for touch and for force. For example, FIG.7 illustrates signals 704 and 706 corresponding to force and touchreflections, respectively, that can be well separated in time (e.g.,such that the force reflections arrive in a dead zone for touchreflections). In practice, an integration of acoustic touch and forcesensing can subject each measurement (touch/force) to noise/interferencefrom the other measurement (force/touch).

In some examples, interference between ultrasonic waves in thedeformable material and the cover glass can be reduced or eliminatedbased on the design of the deformable material. For example, thedeformable material can be selected to have an ultrasonic attenuationproperty above a threshold, such that the signal in the deformablematerial can be damped before reflections in the cover glass arereceived. In some examples, the thickness of the deformable material canbe selected to allow for one or more reflections through the deformablematerial to be received before reflections from the cover glass. In someexamples, the reflection (e.g., first, second, nth) through thedeformable material can be selected such that the reflection of interestoccurs between reflections from the cover glass can be received. In someexamples, an absorbent material can be coupled to the deformablematerial to further dampen ringing of ultrasonic signals in thedeformable material.

FIG. 8A illustrates an exemplary cover glass and a ringing effect thatcan occur in the cover glass. The cover glass 802 can correspond tocover glass 601 and 611 in FIGS. 6A and 6B. Transducer 804 can beconfigured to generate acoustic waves (e.g., shear horizontal waves) andto determine position of a touch from an object in contact with coverglass 802 as described in connection with FIGS. 5A-5C above. Thegenerated acoustic wave can travel initially in the z-axis direction,reflect from the curved bezel of the cover glass 802, and reflect in thedirection of transmitted acoustic wave 808A along the x-axis direction.The transmitted acoustic wave 808A can correspond to the transmit wavepropagation 322 described in connection with FIG. 3B above. An edgereflected wave 808B can correspond to the edge reflected wave 328described in connection with FIG. 3B above. Another portion of theacoustic wave generated by transducer 804 can undergo a series ofreflections within the edge area of the cover glass 802 as illustratedby reflecting energy 806A-806D. These reflections can exhibit similartiming characteristics to the multiple reflections described in FIG. 6C,while the timing between reflections can depend on at least the materialproperties of the cover glass 802, the geometry of the edge area of thecover glass, and the frequency and mode of the transmitted wave. Thesemultiple reflections 806A-806D can be referred to as a ringing signal inthe bezel. As illustrated in FIG. 6C, each subsequent reflection can beattenuated such that the ringing can eventually die down. In someexamples, the initial reflected energy in the ringing signals in thebezel can have significantly more energy (e.g., several orders ofmagnitude more energy) than signals due to reflections from an object(e.g., a finger) contacting the cover glass 802. In some examples, theenergy in the ringing can continue to be high long enough to interferewith reflected energy signals received from objects touching the coverglass. The ringing signals in the bezel can also interfere with theoperation of the force sensor functionality described in FIGS. 6A-6C ifthe ringing signals occur during the Rx time window of the force sensingoperation.

FIGS. 8B and 8C illustrate exemplary mitigation techniques for reducingeffects of the ringing illustrated in FIG. 8A. As illustrated in FIG.8B, the shape of the edge of the cover glass 802 can be designed toreduce the relative amount of reflected energy 806B that returns towardthe transducer 804, and increasing the relative amount of transmittedenergy 808A. For example, a 45-degree angle at the edge of cover glass802 can behave essentially as a flat mirror that produces a consistentangle of reflection of 90 degrees. It should be understood thatflattening even a portion of the edge of cover glass 802 can result inreduced ringing amplitude and that it is not necessary to make the edgeof the cover glass completely flat. Many other cover glass edge shapesare possible and the shape illustrated in FIGS. 8B and 8C are forillustration purposes only. FIG. 8C illustrates the addition of adampening material 810 can also be added somewhere on the cover glassnear where the ringing energy occurs to absorb the ringing energy andcause the ringing to attenuate more quickly. As shown in FIG. 8C, thedampening material can be combined with the cover glass edge shape ofFIG. 8B to significantly improve the ringing performance of the device.

FIG. 9A illustrates a representation of spatial and temporaldistribution of energy received by a transducer 902 due to the ringingeffect described in FIG. 8A. In the illustrated example, the y-axisrepresents a position of received acoustic energy that can be receivedby a transducer 902 positioned at one edge of the electronic device(e.g., transducer 314 above). In FIG. 9A, the width of each of the bars906A-906N can represent an amount of signal (e.g., amount of energy)received by transducer 902 at a particular position in the y-axisdirection. An acoustic wave can be generated by the transducer 902 attime=0. The illustrated bars 906A-906N can represent a signal receivedby the transducer 902, and can correspond to the gradually dampeningbezel ringing signal as described in FIG. 8A and/or the multiplereflections in the force sensor described in FIG. 6C above. For example,when compared to FIG. 6C, the widest bar 906A can correspond to thefirst reflection 622 having the largest amplitude. The appearance ofeach reflection 906A-906N as a continuous bar in the y-axis directionillustrates that the ringing signal is approximately spatially uniformacross the entire length of the transducer 902. Over time, the energy ofthe ringing signal can diminish, as illustrated by bar 906N. The amountof time for the ringing to diminish and the total energy in each of theringing signals can be mitigated by the techniques described in FIG.8B-8C above.

FIG. 9B illustrates a representation of spatial and temporaldistribution of energy received by a transducer 902 during a touchsensing operation. In FIG. 9B, the received signal pattern representedby 908A-908F can correspond to signals reflected by an object in contactwith a cover glass as described above in connection with FIG. 3B. Insome examples, the spacing of the received energy 908A-908F can beaffected by ridges in a user's fingers, orientation of the finger, andthe like. The first received energy returning from the object can berepresented by 908A-908C, which can all occur at the same time on thetime axis. Unlike the ringing energy illustrated in FIG. 9A, thereceived signal caused by an object can be non-uniform along theposition axis, as shown by the three discrete received signal segments908A-908C. In some examples, the position of the received signalsegments 908A-908C can be used to determine the position of the objectin the y-axis direction, and the time of flight can be used to determinethe position of the object in the x-axis direction. Spaces of noreceived energy occurring between received signal segments 908A-908C canbe caused by characteristics of the object, e.g., fingerprints of auser. Although a relatively simple pattern is illustrated for thereceived signal segments 908A-908F, it should be understood that anactual received energy pattern due to an object can be significantlymore complex. The pattern shown is merely for illustrative purposes, andis illustrated to show that there can be a spatial modulation in thereceived signal from an object. The spatial modulation can vary basedon, for example, individual fingerprint patterns, orientation of afinger relative to the acoustic wave propagation direction, amount offorce being applied to the cover glass, and the like. The position ofeach received signal segment 906A-906F on the time axis can correspondto the round trip TOF for transmitted acoustic energy from thetransducer 902 to return to the transducer after being reflected.Furthermore, the amount of time between the first received signal906A-906C and the final received signal 908D-908F can be indicative ofthe size of the object contacting the cover glass. It is important tonote that the ringing signal illustrated in FIG. 9A can be occurringsimultaneously to the signal returning from the object 906A-906F. Theamount of received signal 908A-908F from the object can appearrelatively small compared to the amount of received signal caused by theringing 906A-906N. As will be discussed further below, the spatialmodulation of the received signal from an object 908A-908F can be usedto differentiate between received signal from an object and receivedsignal caused by the ringing.

FIG. 9C illustrates a spatial differential electrode configuration fortransducer electrodes alongside the spatial and temporal distribution ofenergy received by a transducer 902 due to the ringing effect describedin FIGS. 8A and 9A. Although not shown in the figures above, a pair ofelectrodes can be disposed on opposing sides of the transducer that canbe used to both drive the transducer 902 and to receive electricalsignals generated by the transducer. In the simplest configuration, oneof the two electrodes can act as a common electrode, and the second ofthe two electrodes act as both the drive and sense electrode for thetransducer. FIG. 9C illustrates two patterned electrodes 903A-903Bdisposed on a same side of the transducer 902. The patterned electrodes903A-903B are shown with an alternating repeating pattern where eachelectrode 903A and 903B occupies half of the surface of the transducer902. In some examples, the received signal at each of these electrodescan be subtracted to remove the effects of the ringing signals906A-906N. Because of the spatially uniform nature of the ringingsignals (e.g., a solid bar across the entire y-axis), the signal due toringing that is received by each of the electrodes 903A and 903B can beapproximately equal. Thus, in some examples, the ringing signal can becanceled after subtracting the signal values of the two electrodes 903Aand 903B. Signals such as the illustrated ringing signal that have aspatially uniform characteristic can be referred to as common modesignals relative to the electrode pattern 903A and 903B. As mentionedabove, the illustrated ringing signal can correspond to ringing in anedge or bezel area of a cover glass as shown in FIG. 9A, ringing fromthe back edge of the cover glass, ringing in a force sensor such as theringing shown in FIG. 6C, or any other spatially uniform (e.g., commonmode) signal relative to the electrode pattern.

FIG. 9D illustrates the spatial differential electrode configuration fortransducer electrodes alongside the representation of spatial andtemporal distribution of a touch sensing signal corresponding to thetouch sensing operation shown in FIG. 9B. As explained above, thereceived signal segments 908A-908F can return with a spatial modulationpattern that can correspond to characteristics of the object contactingthe cover glass. The electrode pattern for electrodes 903A-903B can beselected to correspond to a particular spatial modulation frequency. Insome examples, by leveraging known spatial modulation characteristicsexpected in the received signal, the electrode pattern 903A-903B can bedesigned to be appropriately sensitive to the received signal. In theillustrated pattern of received signal segments 908A-908F, theelectrodes 903A and 903B can each receive a different amount ofreflected energy because of the pattern. For example, signal segments908A and 908B may primarily be received by electrode 903A, thus causinga difference in the signal on electrodes 903A and 903B. In someexamples, by subtracting the signals received by the two electrodes903A/903B a differential touch signal based on the energy reflected bythe object can be produced. At the same time, because the electrodes903A and 903B can receive the same signals from the ringing 906A-906N,the ringing component of received signal can be canceled. In someexamples, this scheme can be more effective in reducing the impact ofringing on the detecting touch sensing output than the mitigationmeasures illustrated in FIGS. 8B and 8C. Alternatively, the combinedeffect of the spatial differential electrode configuration and themitigation measures illustrated in FIGS. 8B and 8C can be used tomaximize signal to noise ratio values of the acoustic touch sensingsystem.

As can be seen in the configuration of electrodes 903A and 903B in FIGS.9C-9D, the electrodes can form a repeating pattern with a certain pitchalong the y-axis direction. The pitch of the electrodes can have acorresponding spatial frequency to which differential measurement of theelectrodes 903A and 903B can be responsive. In other words, theelectrodes 903A and 903B can be designed to be tuned to a particularspatial frequency. For example, ridges on a human finger can produce aspatial frequency within a particular range of frequencies that cancorrespond to the typical spacing of ridges that form a fingerprint. Atypical range of fingerprint ridge spacing can be between 200 μm and 700μm. Accordingly, the spacing or pitch of the electrodes 903A and 903Bbeing used for touch measurement can be tuned to an appropriate spatialfrequency that lies within the range of spatial frequencies expected tobe produced by a human finger. In addition, as will be discussed in moredetail below, multiple electrode patterns of different pitch, electrodepatterns with a configurable pitch, or a combination of both can be usedto selectively tune the sensitivity of a differential measurement to aplurality of spatial frequencies.

FIGS. 10A-10B illustrate exemplary spatial differential force sensingconfigurations according to examples of the disclosure. As discussedimmediately above, the pitch of electrodes 1003A and 1003B can determinea spatial frequency sensitivity for differential measurements of thetransducer 1010. As also described above, the spatial frequenciesproduced by fingerprint ridges can be used to perform touch measurementwith an appropriately tuned electrode configuration. As a reminder, theforce measurement described in FIGS. 3 and 6A-6C utilize a deformablematerial (e.g., 316 and 614) with a uniform physical characteristic.Unlike the signals reflected from a fingerprint, a uniform deformablematerial as described above may produce only a DC or common mode spatialfrequency as a result of reflected energy.

FIG. 10A illustrates a first deformable material configuration forintroducing a spatial frequency into the deformable material comprisingfirst sections 1014A and second sections 1014B. In addition, FIG. 10Aillustrates a corresponding electrode configuration of electrodes 1003Aand 1003B (which can correspond to electrodes 903A and 903B above) thatcan be tuned to the spatial frequency created by the pattern in thedeformable material. In some examples, the electrodes 1003A and 1003Bcan be coupled to one side of transducer 1010, and a second electrode1011 can be disposed on the opposite side of the transducer. In someexamples, the second electrode 1011 can be connected to ground. In someexamples, as will be described in more detail below regarding FIGS.14A-14B, the second electrode 1011 can be operated as a floatingelectrode. Furthermore, as will be described in more detail below,multiple electrodes 1011 can be disposed on the opposite side of thetransducer 1010 and connected in different ways.

In some examples, a spatial frequency associated with the deformablematerial 1014 can be introduced by varying the thickness of thedeformable material between the first sections 1014A and 1014B as shownin FIG. 10. In some examples, the difference in thickness of the firstsections 1014A and second sections 1014B can introduce a difference timeof flight based on the different distances traveled by a travellingacoustic wave. In some examples, the thicknesses can be configured tocreate a half-wavelength difference in round trip time of flight betweenthe first sections 1014A and the second sections 1014B. As describedabove in FIGS. 9A-9D, the electrodes 1003A and 1003B can be readdifferentially to eliminate the effects of common mode signals such as aringing signal in a bezel as described in FIGS. 8A-8C. In some examples,the half-wavelength difference in time of flight in the first sections1014A and second sections 1014B can result effectively in a summationwhen the differential measurement is performed between the electrodes1003A and 1003B. In some examples, the electrodes 1003A and 1003B canalso be used for touch detection in addition to force detection. In someexamples, the electrodes 1003A and 1003B can be grouped together toperform touch sensing measurements. In some examples, electrodes 1003Aand 1003B can be added together to perform touch detection. In someexamples, force detection in the deformable material 1014A and 1014B canbe performed during a ring-down period of the bezel reflectionsdescribed above in FIGS. 8A-8C. During the ring-down period, thedifferential measurements being performed can cancel out the common modebezel reflection signals as described above. In some examples, after thering-down period, the touch sensing operation using combined electrodes1003A and 1003B or the summation of electrodes 1003A and 1003B. In someexamples, the spatial frequency selected for the deformable material canbe selected to be orthogonal to one or more spatial frequencies used fordetecting touch in a touch sensing mode. In some examples, an optionalisolation material 1012 can be placed between the first sections 1014Aand the second sections 1014B of the deformable material to preventinteractions between the waves traveling in the separate sections.

FIG. 10B illustrates an alternative configuration for introducing aspatial frequency associated with the deformable material 1014 byvarying the speed of sound between the first sections 1014A and secondsections 1014B of the deformable material. In some examples, theelectrodes 1003A and 1003B, transducer 1010, and second electrode 1011can be configured in the same was as described in FIG. 10A above. Insome examples, the speed of sound between the first and second sectionscan be achieved by placing a first material in the first sections 1014Aand a second, different material with a different speed of sound in thesecond sections 1014A. In some examples, the differences of speed ofsound of the first sections 1014A and second sections 1014B can resultin different time of flight of acoustic waves travelling in therespective sections. In some examples, the speed of sounds can beselected such that the round trip time of flight difference between thefirst sections 1014A and the second sections 1014B is half-wavelength ofthe transmitted acoustic wave. In some examples, the speed of sounds canbe selected such that the time of flight difference between the firstsections 1014A and second sections 1014B is equal to multiplewavelengths of the transmitted acoustic wave. For example, one of thematerials can be silicone, while the second material can be air. Asdescribed above in FIGS. 9A-9D, the electrodes 1003A and 1003B can beread differentially to eliminate the effects of common mode signals suchas a ringing signal in a bezel as described in FIGS. 8A-8C. In someexamples, the ½ wavelength difference in time of flight in the firstsections 1014A and second sections 1014B can result effectively in asummation when the differential measurement is performed between theelectrodes 1003A and 1003B. In some examples, the electrodes 1003A and1003B can also be used for touch detection in addition to forcedetection. In some examples, the electrodes 1003A and 1003B can begrouped together to perform touch sensing measurements. In someexamples, electrodes 1003A and 1003B can be added together to performtouch detection. In some examples, force detection in the deformablematerial 1014A and 1014B can be performed during a ring-down period ofthe bezel reflections described above in FIGS. 8A-8C. During thering-down period, the differential measurements being performed cancancel out the common mode bezel reflection signals as described above.In some examples, after the ring-down period, the touch sensingoperation using combined electrodes 1003A and 1003B or the summation ofelectrodes 1003A and 1003B. In some examples, the spatial frequencyselected for the deformable material can be selected to be orthogonal toone or more spatial frequencies used for detecting touch in a touchsensing mode. In some examples, an optional isolation material 1012 canbe placed between the first sections 1014A and the second sections 1014Bof the deformable material to prevent interactions between the wavestraveling in the separate sections.

FIGS. 11A-11E illustrate electrode arrangement grouping patterns forsingle-sided, spatial differential electrode configurations according toexamples of the disclosure. FIGS. 9C-9D and FIGS. 10A-10B bothillustrate single-sided differential electrode patterns, and both touchsensing and force sensing operations associated with the single-sideddifferential electrode patterns have been described above. FIG. 11Aillustrates an exemplary two-electrode spatial differential electrodeconfiguration according to examples of the disclosure. The alternatingtwo-electrode configuration can include electrodes 1103A and 1103B,which can correspond to electrodes 903A and 903B in FIGS. 9C-9D aboveand electrodes 1003A and 1003B in FIGS. 10A and 10B above. Groupingpattern 1105A illustrates an exemplary differential connection patternthat can be used to perform spatial differential sensing for touch asdescribed above in connection to FIGS. 9C-9D or for force as describedabove in connection to FIGS. 10A-10B. In some examples, the electrode1103A can be coupled to a first terminal (e.g., positive) of adifferential amplifier, and the electrode 1103B can be connected to asecond terminal (e.g., negative) of the differential amplifier. Itshould be understood that the positive/negative connections of thedifferential amplifier can be reversed without departing from the scopeof the present disclosure. The right hand side of each FIG. 11A-11Eillustrates a finger spatial frequency curve 1107 that can approximatethe energy density of various spatial frequencies produced by fingerreflections. The bar 1109A illustrates one possibility for the spatialfrequency that can correspond to the pitch of electrodes 1103A and1103B. In the illustrated bar 1109A, the spatial frequency thatcorresponds to the pitch of electrodes 1103A and 1103B can be placed atthe peak of the finger spatial frequency curve to maximize the amount ofsignal obtained during a touch operation. However, it should beunderstood from the disclosure above in FIGS. 10A-10B that the spatialfrequency can be adjusted (e.g., by changing the pitch) to correspond toa spatial frequency of a deformable material pattern (e.g., 1014A and1014B above) in order to tune the spatial frequency sensitivity to forcesensing. It should be understood that the physical metal layers used toform the electrodes 1103A and 1103B are fixed once the metal layers areformed into the electrode patterns. Accordingly the physical size of themetal layers that form electrodes themselves cannot be dynamicallychanged to change the spatial frequency sensitivity. However, as will bedescribed below in connection with FIGS. 11B-11E, 13B and 17-20, thespatial frequency and phase sensitivity can be dynamically configurableby changing electrode groupings as will be described in more detailbelow.

FIG. 11B illustrates an exemplary four electrode spatial differentialelectrode configuration according to examples of the disclosure. In someexamples, the electrodes 1103C-1103E can be disposed on a single side ofa transducer (e.g., 612, 902, or 1010 above) with a common electrode onthe opposite side of the transducer. The electrodes 1103C-1103E can beplaced in an alternating and repeating pattern as indicated by the fillpatterns corresponding to each electrode. Grouping patterns 1105B and1105C illustrated two exemplary differential connection patterns thatcan be used to perform spatial differential sensing tuned to multiplespatial frequencies.

Grouping pattern 1105B illustrates an alternating pattern similar toconnection pattern 1105A in FIG. 11A. This connection pattern can beachieved by combining the outputs of electrodes 1103C with the outputsof electrode 1103E and connecting the combined electrode to one terminalof a differential amplifier (e.g., positive). At the same time, theoutputs of electrodes 1103D and 1103F can be combined and the combinedelectrode can be connected to the opposite terminal of the differentialamplifier (e.g., negative). Grouping pattern 1105C illustrates a secondexemplary pattern can be configured to produce a different effectiveelectrode pitch (and corresponding spatial frequency sensitive) usingthe same electrodes as pattern 1105B. In the grouping configuration1105C, the electrodes 1103C and 1103D can be combined and connected to afirst terminal of a differential amplifier (e.g., positive), andelectrodes 1103E and 1103F can be combined and connected to a secondterminal of the differential amplifier (e.g., negative). The pitch ofthe resulting pattern can be twice as long as the pitch of the patternresulting from grouping pattern 1105B. Thus, by switching the electrodeconfigurations between grouping pattern 1105A and 1105B, the spatialfrequency sensitivity of the spatial differential electrodeconfiguration can be dynamically changed. Bars 1109B and 1109C plottedagainst the finger spatial frequencies curve 1107 illustrate anexemplary set of spatial frequencies that can correspond to thegroupings 1105B and 1105C respectively. In the illustrated bars, both ofthe bars fall near the peak of the spatial frequency curve 1107.However, because the relative sizing of the grouping patterns can changeby a factor of two between the two groupings and the resulting ratio ofthe spatial frequencies corresponding to bars 1109B and 1109C can alsobe 2:1.

FIG. 11C illustrates an exemplary electrode spatial differentialelectrode configuration with six electrodes respectively according toexamples of the disclosure. In some examples, the electrodes 1103G-1103Lcan be disposed on a single side of a transducer (e.g., 612, 902, or1010 above) with a common electrode on the opposite side of thetransducer. The electrodes 1103G-1103L can be placed in an alternatingand repeating pattern as indicated by the fill patterns corresponding toeach electrode. As should be understood based on the descriptions ofFIG. 10B above, the grouping configurations 1105D and 1105E can beconnected to terminals of a differential amplifier. The pitch of theillustrated patterns can have a ratio of 3:2, and corresponding bars1109D and 1109E are illustrated along with the finger spatial frequencycurve 1107. Although the difference may appear subtle, in the graphs ofFIG. 11B and FIG. 11C, the groupings in FIG. 11C show that by reducingthe ratio of effective pixel pitch (e.g., from 2:1 to 3:2), the sensedspatial frequencies can be closer together, and in some examples, anincreased in amount of signal can be obtained.

FIG. 11D-11E illustrate exemplary electrode spatial differentialelectrode configuration with eight and twelve electrodes respectivelyaccording to examples of the disclosure. As should be understood basedon the FIGS. 11A-11C above, the electrodes can be grouped into differentgroupings (e.g., 1105F-1105H in FIGS. 11D and 1105I-1105M in FIG. 11E)to maximize an amount of signal obtained within the desirable frequencyrange. For example, the bars 1109J-1109M can correspond to fourdifferent spatial frequencies within the finger spatial frequency curve1107 peak. In some examples, the bar 11091, which is shown positionedaway from the spatial frequency curve 1107 peak can be used for forcesensing. As explained above, the deformable material in FIGS. 10A-10Bcan be configured with a desired spatial frequency, and by placing thedesired frequency outside of the finger spatial frequency curve 1107peak, the touch and force signals have a reduced amount of interferencewith one another.

FIG. 12A illustrates an exemplary configuration for a spatialdifferential electrode configuration having differential electrodes onboth sides of a transducer 1210 according to examples of the disclosure.FIG. 12 depicts a flattened view of a cover glass 1202, transducer 1210,and a deformable material 1214 that can correspond to the cover glass,transducer, and deformable material components in FIGS. 3B and 6B.Furthermore the deformable material 1214 is depicted with a jaggedborder to illustrate that a spatial frequency has been included in thedeformable material 1214. It should be understood that either of theconfigurations in FIGS. 10A and 10B for including a spatial frequency inthe deformable material 1214 can be used while remaining within thescope of the present disclosure. The illustrated jagged shape of thedeformable material 1214 is merely illustrative of a pitch of theassociated spatial frequency. FIG. 12 illustrates a transducer 1210having two sets of two electrode differential patterns, electrodes 1203Aand 1203B on a first side of the transducer, and electrodes 1207A and1207B on a second side of the transducer. As illustrated, the first sideelectrodes 1203A/1203B can be disposed between the transducer and thecover glass 1202 and the second side electrodes 1207A/1207B can bedisposed between the transducer and the deformable material 1214. Itshould be recognizable that each of the pairs of electrodes 1203A/1203Band 1207A/1207B respectively can correspond to a two pixel differentialelectrode configuration as shown in FIG. 11A above. As illustrated the1207A/1207B can have a larger electrode size and a corresponding largerelectrode pitch, leading each of the electrode pairs to have a differentcorresponding spatial frequency. Furthermore, in some examples, thepitch of the electrodes 1207A and 1207B can be configured to match thespatial frequency associated with the deformable material.

FIG. 12B illustrates an exemplary connection pattern for performingacoustic wave transmission, touch measurement, and force measurements.In an exemplary transmit state an acoustic wave can be transmitted byproviding a differential driving signal across the transducer 1210. Thiscan be accomplished by differentially driving electrodes on one side(e.g., 1203A and 1203B) of the transducer 1210 with a first polarity ofa transmit signal and driving electrodes (e.g., 1207A and 1207B) on theopposite side with the opposite polarity of the transmit signal. Whilethe chart illustrates 1203A/1203B connected to the positive inputterminal and 1207A/1207B connected to the negative input terminal, thesepolarities can be switched without departing from the scope of thepresent disclosure. In some examples, a single-sided transmit can beaccomplished by driving a set of electrodes on one side of thetransducer (e.g., either 1203A/1203B or 1207A/1207B) with a transmitsignal and coupling the opposite set of electrodes to ground.

In a first exemplary force measurement configuration, the electrode1207A can be coupled to a first input terminal of a differentialamplifier and the electrode 1207B can be coupled to a second inputterminal of a differential amplifier. In the first exemplary forcemeasurement configuration, the electrodes 1203A and 1203B can be coupledto ground. In a second exemplary force measurement configuration, one ofthe electrodes (e.g., 1207A or 1207B) can be coupled to a single-endedamplifier, and the other electrode (e.g., 1207B or 1207A) can be coupledto ground. In the second exemplary force measurement configuration, theelectrodes 1203A and 1203B can be left floating to create a differentialmeasurement in the charge domain as will be explained in more detailwith regard to FIGS. 14B and 14C below.

In a first exemplary touch measurement configuration, the electrode1203A can be coupled to a first input terminal of a differentialamplifier and the electrode 1203B can be coupled to a second inputterminal of a differential amplifier. In the first exemplary forcemeasurement configuration, the electrodes 1207A and 1207B can be coupledto ground. In a second exemplary force measurement configuration, one ofthe electrodes (e.g., 1203A or 1203B) can be coupled to a single endedamplifier, and the other electrode (e.g., 1203B or 1203A) can be coupledto ground. In the second exemplary force measurement configuration, theelectrodes 1207A and 1207B can be left floating to create a differentialmeasurement in the charge domain as will be explained in more detailwith regard to FIGS. 14B and 14C below.

FIGS. 13A and 13B illustrated exemplary configurations and groupings fordouble-sided differential electrode configurations according to examplesof the disclosure. FIG. 13A illustrates a configuration with twoelectrodes 1303A and 1303B on a first (e.g., top) side of the transducer1310 and two electrodes 1307A and 1307B on a second (e.g., bottom) sideof the transducer. The electrode pairs can be operated similarly to thetwo-sided electrode operation described in FIG. 12 with grouping pattern1305A for the electrodes 1303A and 1303B and grouping pattern 1313A forthe electrodes 1307A and 1307B. In some examples, the top-sideelectrodes (e.g., 1303A and 1303B) and bottom-side electrodes (e.g.,1307A and 1307B) can have a different pitch, and thus differentcorresponding spatial frequency sensitivity. The example in FIG. 13Ashows a ratio of 2:1 between the pitch of the bottom electrodes and thetop electrodes. The chart in the right hand side of FIG. 13A illustratesa finger spatial frequency curve 1308 that can correspond to the fingerspatial frequency curve 1107 in FIGS. 11A-11E above. In the particularexample of FIG. 13A, the top electrodes 1303A/1303B can be designed tosense a spatial frequency 1309A at the peak of the finger spatialfrequency curve 1308. Furthermore, the bottom electrodes 1307A/1307B canbe designed to sense a spatial frequency 1311A that can be away from thepeak of the finger spatial frequency curve 1308. Furthermore, thespatial frequency corresponding to 1311A can be the spatial frequencyassociated with the deformable material pattern (e.g., 1204 above) asfurther described in FIGS. 10A-10B.

FIG. 13B illustrates a configuration with four electrodes 1303C-1303F ona first (e.g., top) side of transducer 1310 and six electrodes1307G-1307L on a second side (e.g., bottom of transducer 1310. Thefour-electrode configuration can correspond to the electrodeconfiguration illustrated in FIG. 11B and the six-electrodeconfiguration can correspond to the electrode configuration illustratedin FIG. 11C. In some examples, electrode groupings 1305B, 1305C, 1313B,and 1313C can be used to obtain measurements at four different spatialfrequencies. It should be understood that the transmit, forcemeasurement, and touch measurement states described in FIGS. 12A and 12Bcan be implemented with the electrode groupings in an analogous way tothe connections in FIG. 12B. As one example, the force measurement ofFIG. 12B can be accomplished using pixel grouping 1313C. In someexamples, the electrodes 1307G, 1307H, and 1307I can be grouped togetherand coupled to a first input terminal of a differential amplifier andthe electrodes 1307I, 1307K, and 1307L can be grouped together andcoupled to a second terminal of the differential amplifier. The chart inthe right hand side of FIG. 13B illustrates a finger spatial frequencycurve 1308 that can correspond to the finger spatial frequency curve1107 in FIGS. 11A-11E above. In some examples, the spatial frequency forgrouping 1313C can be located at the position of the bar 1311B, which isat a spatial frequency far from the peak of the finger spatial frequencycurve 1308. In some examples, the spatial frequency associated with1311B can be the frequency associated with the deformable materialpattern (e.g., 1204 above), as further described in FIGS. 10A-10B. Theremaining groupings 1305B, 1305C, and 1313B can also be used to producemeasurements at additional spatial frequencies as reflected by bars1309B-1309D, which can all be positioned near the peak of the fingerspatial frequency curve 1308 to maximize an amount of signal for touchmeasurement.

FIGS. 14A-14C illustrate exemplary amplifier configurations forperforming differential sensing according to examples of the disclosure.FIG. 14A illustrates an exemplary differential amplifier readoutconnection for a two-pixel electrode pattern 1403A and 1403B disposed ona first side of a transducer 1410. In some examples, a ground electrode1407 can be disposed on the opposite side of the transducer 1410. Itshould be understood from the disclosure above, including FIGS. 12 and13, that the electrode 1407 could be representative of a multipleelectrode configuration (e.g., as described in FIGS. 11A-11E) where allof the individual electrodes are connected to ground. In some examples,the use of a differential amplifier to read out the signals fromelectrodes 1403A and 1403B can result in a large amount of noise.Furthermore, in some examples, the differential amplifier must be ableto accept a large amount of common mode signal at the differentialinputs (e.g., from the ringing signal described in FIGS. 8A-8C.

FIG. 14B illustrates an alternative single-ended amplifier configurationfor performing differential sensing according to examples of thedisclosure. In the illustrated configuration, one of the two electrodes1403A/1403B can be connected to a single ended amplifier 1413, and theother of the two electrodes 1403B/1403A can be connected to ground. Theelectrode on the opposite side 1407 of the transducer 1410 can befloating instead of connected to ground as shown in FIG. 14A. Inaddition, an optional grounded shield 1414 can be provided frompreventing coupling of signals into the floating electrode 1407 that canget injected into the signal received at the amplifier 1413. In someexamples, when the optional grounded shield 1414 is provided, aninsulating layer 1409 can be disposed between the grounded shield andthe floating electrode 1407 to electrically isolate the grounded shieldfrom the floating electrode. FIG. 14C illustrates an equivalent circuitof the configuration in FIG. 14B. FIG. 14C shows a voltage signal formedbetween electrode 1403A and the floating electrode 1407 having a valueV_(CM)+V_(D)/2 and a voltage formed between electrode 1403B (which canbe grounded) and the floating electrode having a value V_(CM)−V_(D)/2.V_(CM) represents a common mode voltage that can be a result of signalsthat are common to the two electrodes 1403A and 1403B such as ringing inthe bezel described in FIGS. 8A-8C above. V_(D) represents adifferential voltage between the first and second electrode that canresult from the electrodes 1043A and 1403B receiving different signalsdue to spatial modulation of the incoming signal (e.g., from a finger)as described above. In some examples, when the electrode 1403B isgrounded and the floating electrode 1407 is at a floating potential, thesingle ended amplifier sees the voltages in series, with the common modesignal effectively canceling out, and the differential components addingtogether. The voltage (V_(A)) at the input of amplifier 1413 can beexpressed with the following equations:

$\begin{matrix}{V_{A} = {( {V_{CM} + \frac{V_{D}}{2}} ) - ( {V_{CM} - \frac{V_{D}}{2}} )}} & (1) \\{{( {V_{CM} + \frac{V_{D}}{2}} ) - ( {V_{CM} - \frac{V_{D}}{2}} )} = V_{D}} & (2) \\{V_{A} = V_{D}} & (3)\end{matrix}$

The equations show that the common mode term can be canceled, and thevoltage at the amplifier input can be equal to the differential voltagebetween the electrodes 1403A and 1403B. Thus, a single-ended amplifiercan be used to perform the differential measurement, and the amplifierdoes not need to handle the signal swing of the full common-mode signal,which can be orders of magnitude larger than the differential signal asdescribed in FIGS. 8A-8C above. It should be understood from thedisclosure above that the single-ended amplifier configuration of FIGS.14B and 14C is not limited to the situation of a two-electrode patternon one side of the transducer 1410, but can be extended to any of thesingle-sided or double-sided electrode patterns described in FIGS.11A-11E and 13A-13B and other electrode patterns capable of performingthe differential sensing described throughout the disclosure.

FIG. 14D illustrates an alternative amplifier configuration forperforming differential sensing according to examples of the disclosure.In the illustrated configuration, the two electrodes 1403A and 1403B canbe connected to a differential amplifier 1412, instead of the singleended amplifier 1413 of FIG. 14B. The other components of theconfiguration illustrated in FIG. 14D can be the same as theconfiguration illustrated in FIG. 14B. However unlike in theconfiguration of FIG. 14B, the signals may not be referenced to a knownpotential, as the floating electrode 1407 is floating at the time ofmeasurement. In this case, the differential amplifier 1412 may need tobe capable of accepting a wider range of input voltage values. Inparticular, the floating electrode 1407 can be influenced by couplingwith nearby objects. As mentioned above, an optional grounded shield1414 can be used to shield the floating electrode 1407 from couplingwith nearby objects. In some examples, when the optional grounded shield1414 is provided, an insulating layer 1409 can be disposed between thegrounded shield and the floating electrode 1407 to electrically isolatethe grounded shield from the floating electrode. However, the optionalgrounded shield 1414 can create a leakage path for charge via capacitivecoupling to the floating electrode 1407. Accordingly, there can be atrade-off between rejecting outside object coupling and common moderejection in the floating electrode 1407 configuration. In light ofthese trade-offs, in some examples, a common-mode feedback approach asdescribed in FIGS. 14E-14F below can be used as an alternative to thefloating electrode configuration for reducing effects of a common-modesignal in during spatial-differential readout according to examples ofthe disclosure

FIGS. 14E-14F illustrate exemplary amplifier configurations with acommon-mode feedback (CMFB) configuration for performing spatialdifferential sensing according to examples of the disclosure. FIG. 14Eillustrates an exemplary differential amplifier 1412 readout connectionfor a two-pixel electrode pattern 1403A and 1403B disposed on a firstside of a transducer 1410. In some examples, an electrode 1407 can bedisposed on the opposite side of the transducer 1410. In some examples,the signals from electrodes 1403A and 1403B can result include a largecommon mode signals as described above (e.g., ringing in the bezel asdescribed with reference to FIGS. 8A-8C above). These common modesignals can be reduced or eliminated by the CMFB configurationillustrated in FIG. 14E. For example, the common mode signal fromelectrodes 1403A and 1403B can be sensed by resistors 1414A and 1414B,respectfully. In some examples, resistors 1414A and 1414B can be thesame size or substantially the same size. In some examples, resistors1414A and 1414B can be a generic impedance that can include resistors,capacitors, and/or inductors. The sensed common mode signal (V_(CM))(can be coupled to the first terminal (e.g., negative or inverting) ofoperational amplifier 1416, and the second terminal (e.g., positive ornon-inverting) of operational amplifier 1416 can be coupled to a desiredreference voltage 1420 (e.g., ground or any other desired voltage). Insome examples, the output of operational amplifier 1416 can be connectedto electrode 1407 on one side of the transducer. In some examples, whenthe second terminal (e.g., positive) of operational amplifier 1416 iscoupled to ground, the common mode signal can be eliminated or reducedby the operational amplifier. As discussed above with reference to FIG.14C, a voltage signal can be formed between electrode 1403A andelectrode 1407 having a value V_(CM)+V_(D)/2 and a voltage can be formedbetween electrode 1403B and electrode 1407 also having a valueV_(CM)−V_(D)/2. Because the configuration illustrated in FIG. 14E caneliminate V_(CM), amplifier 1412 can receive only V_(D)—the differentialvoltage between the first and second electrode that can result from theelectrodes 1403A and 1403B receiving different signals due to spatialmodulation of the incoming signal (e.g., from a finger) as describedabove. The voltage (V_(A)) at the input of amplifier 1412 can beexpressed with the following equations:

V _(A)=(V _(CM) +V _(D)/2)−(V _(CM) −V _(D)/2)  (1)

V _(A)=(0+V _(D)/2)−(0−V _(D)/2)  (2)

V _(A) =V _(D)/2+V _(D)/2  (3)

V _(A) =V _(D)  (4)

The equations show that the common mode term can be eliminated orreduced, and the voltage at the input of amplifier 1412 can be madeequal to the differential signal component between the electrodes 1403Aand 1403B (e.g., V_(D)). Thus, amplifier 1412 does not need to have tobe designed to accomodate the voltage range of common-mode signal, whichcan be orders of magnitude larger than the differential signal asdescribed in FIGS. 8A-8C above. It should be understood from thedisclosure above, including FIGS. 12 and 13, that the electrode 1407could represent a multiple electrode configuration (e.g., as describedin FIGS. 11A-11E).

FIG. 14F illustrates a CMFB configuration for performing differentialsensing according to examples of the disclosure. In some examples,resistors 1414A and 1414B can reduce the impedance seen at the input ofdifferential amplifier 1412, and cause errors. In some examples, 1414Aand 1414B can introduce thermal noise at the input of amplifier 1412that can be amplified by the differential amplifier 1412. In theillustrated configuration, buffers 1418A and 1418B can be used toisolate resistors 1414A/1414B from the inputs of differential amplifier1412). This configuration can isolate resistors 1414A/1414B fromamplifier 1412 such that resistors 1414A/1414B do not interfere withdifferential amplifier 1412 and the differential amplifier does not seethe resistance of the resistors 1414A/1414B. Moreover, the positiveterminal of feedback operational amplifier 1416 can be coupled to groundor a reference voltage source 1420 that can provide any desiredreference voltage. The CMFB circuit illustrated in FIG. 14F can be usedto remove or reduce the common mode signal component from the input todifferential amplifier 1412. Thus, when the CMFB circuit is employed,amplifier 1412 does not need to be able to accept the full common-modesignal swing.

It should be understood from the disclosure above that the CMFBconfigurations of FIGS. 14E and 14F are not limited to the situation ofa two-electrode pattern on one side of the transducer 1410, but can beextended to any of the single-sided or double-sided electrode patternsdescribed in FIGS. 11A-11E and 13A-13B as well as other electrodepatterns capable of performing the differential sensing describedthroughout the disclosure

FIGS. 15A-15C illustrate a spatial null phenomenon that can beassociated with spatial differential electrode configurations accordingto examples of the disclosure. FIGS. 16A and 16B illustrate asingle-sided electrode pattern having four electrodes 1603A-1603D thatcan correspond to the four-electrode pattern illustrated in FIG. 11Babove, and in particular the grouping 1105C. FIG. 15A illustrates apoint source 1520 of acoustic energy. Acoustic energy from the pointsource 1520 can radiate in a radiating pattern 1522, and for some pointsource locations, the point source 1520 can be aligned with the centerof one of the segments of an electrode (e.g., 1503B). FIG. 15Billustrates a point source 1520 aligned between two adjacent segments1503A and 1503B. In some examples, when the point source 1520 is alignedbetween the two electrodes, equal amounts of signal from the pointsource can produce equal amounts of signal on each electrode. In someexamples, when the two electrodes are sensed differentially, the signalfrom the point source can be canceled. FIG. 15C illustrates a pluralityof spatial nulls 1524 that can occur for point source locations thatfall on the edge of the alternating electrode pattern of electrodes1503A and 1503B. Although a point source 1520 is described in connectionwith the figures above, it should be understood that a similar effectcan occur as a result of reflections from an object touching the coverglass 1502, particularly when the contact by the object is centeredalong one of the spatial nulls 1524. Furthermore, it should beunderstood that the same spatial null phenomenon can occur not only atthe intersection points between individual electrodes, but also atintersection points of electrode groupings in the various groupingconfigurations (e.g., 1105A-1105M, 1305A-1305C, and/or 1313A-1313C).

FIGS. 16A-16D illustrate an exemplary quadrature spatial differentialelectrode configuration according to examples of the disclosure. FIG.16A depicts a four electrode spatial differential electrodeconfiguration that can correspond to the electrode configuration in FIG.11B and in particular the electrode grouping 1105C. As illustrated, theelectrodes 1603A and 1603B are grouped together and can be connected toa first terminal of a differential amplifier, and the electrodes 1603Cand 1603D are grouped together and can be connected to a second terminalof a differential amplifier. Similar to the illustration in FIG. 15B, apoint source 1620 is illustrated at the intersection between theelectrode groups. FIG. 16B illustrates corresponding spatial nulls 1624,and it can be seen that the point source 1620 in FIG. 16A can fallwithin one of the spatial nulls illustrated in FIG. 16B. In someexamples, signal measurements by the first electrode grouping show inFIGS. 16A-16B can be referred to as the in-phase component.

FIG. 16C illustrates the same spatial differential electrodeconfiguration with a second grouping having shifted spatial nullsaccording to examples of the disclosure. In FIG. 16C, the point sourcelocation on the cover glass 1602 is identical to the location in FIG.16A. The grouping of the electrodes has the same pitch as the groupingin FIG. 16A, but the pattern is shifted by 90 degrees (e.g., one quarterof the total pitch) in the spatial domain. As illustrated, electrodes1603A and 1603D are grouped together and can be connected to a firstterminal of a differential amplifier, and the electrodes 1603B and 1603Care grouped together and can be connected to a second terminal of adifferential amplifier. The overall pitch of the electrode grouping isthe same as in FIG. 16A, and thus the spatial frequency corresponding tothe grouping remains the same, but the spatial phase is changed. Thespatial phase of the grouping is illustrated by the shifted spatialnulls 1626 in FIG. 16D. In some examples, signal measurements by thesecond electrode grouping show in FIGS. 16C-16D can be referred to asthe quadrature component. The position of the spatial nulls 1624 andshifted spatial nulls 1626 can be made non-overlapping, such that anypoint source 1620 location on the cover glass 1602 can fall outside of aspatial null in at least one of the two electrode configurations. Insome examples, the in-phase and quadrature components can be addedtogether to eliminate any signal nulls regardless of the position of thesignal source.

FIGS. 17A-17C illustrates a first exemplary spatial electrodeconfiguration for performing quadrature spatial differentialmeasurements of touch signals on cover glass 1702 and force sensingusing a shared set of electrodes according to examples of thedisclosure. In some examples, an eight-electrode configuration asdescribed in FIG. 11D can be used. FIGS. 17A and 17B illustrate thein-phase and quadrature electrode grouping configurations described inFIGS. 16A-16D. In the in-phase configuration, electrodes 1703A, 1703B,1703E and 1703F can be grouped together and electrodes 1703C, 1703D,1703G, and 1703H can be grouped together. In the quadratureconfiguration, electrodes 1703A, 1703D, 1703E, and 1703H can be groupedtogether and electrodes 1703B, 1703C, 1703F, and 1703G can be groupedtogether. In some examples, the deformable material 1714 can include aspatial pattern as described in FIGS. 10A-10B having a correspondingspatial frequency. It should be understood that while the jagged shapeof the deformable material 1714 in FIGS. 17A-17C imply a spatial patternbased on thickness variations of the deformable material, any of thetechniques for including a spatial pattern in the deformable material astaught in FIGS. 10A-10B can be used. The illustrated jagged shape of thedeformable material 1714 is merely illustrative of the pitch of theassociated spatial pattern. FIG. 17C illustrates an exemplary electrodegrouping for performing touch sensing, the electrode grouping beingmatched to the pitch of the deformable material 1714 spatial pattern. Insome examples, the electrodes 1703A-1703D can be grouped together andthe electrodes 1703E-1703H can be grouped together and connected to adifferential amplifier for performing force sensing using the deformablematerial as described in FIGS. 3B, 6A-6B and 10A-10B above. Theelectrode grouping of FIG. 17C can result in force sensing at a lowerspatial frequency than the touch sensing because the spatial pattern ofthe deformable material 1714 has a larger pitch than the pitch used fortouch sensing.

FIGS. 18A-18C illustrate a second exemplary spatial electrodeconfiguration for performing quadrature spatial differentialmeasurements of touch signals on cover glass 1702 and force sensingusing a shared set of electrodes according to examples of thedisclosure. In some examples, a four-electrode configuration asdescribed in FIG. 11B can be used. FIGS. 18A and 18B illustrate thein-phase and quadrature electrode grouping configurations described inFIGS. 16A-16D. In the in-phase configuration, electrodes 1803A and 1803Bcan be grouped together and electrodes 1803C and 1803D can be groupedtogether. In the quadrature configuration, electrodes 1803A and 1803Dcan be grouped together, and electrodes 1803B and 1803C can be groupedtogether. In some examples, the deformable material 1814 can include aspatial pattern as described in FIGS. 10A-10B having a correspondingspatial frequency. It should be understood that while the jagged shapeof the deformable material 1814 in FIGS. 18A-18C imply a spatial patternbased on thickness variations of the deformable material, any of thetechniques for including a spatial pattern in the deformable material astaught in FIGS. 10A-10B can be used. The illustrated jagged shape of thedeformable material 1814 is merely illustrative of the pitch of theassociated spatial pattern. FIG. 18C illustrates an exemplary electrodegrouping for performing touch sensing, the electrode grouping beingmatched to the pitch of the deformable material 1714 spatial pattern. Insome examples, the electrodes 1803A and 1803C can be grouped togetherand the electrodes 1803B and 1803D can be grouped and connected to adifferential amplifier for performing force sensing using the deformablematerial as described in FIGS. 3B, 6A-6B and 10A-10B above. Theelectrode grouping of FIG. 17C can result in force sensing at a higherspatial frequency than the touch sensing because the spatial pattern ofthe deformable material 1814 has a smaller pitch than the pitch used fortouch sensing.

It should be understood that although one set of electrodes is shown inFIGS. 17A-17C and 18A-18C for performing both touch sensing and forcesensing, the two-sided electrode configurations shown in FIGS. 12 and13A-13B can also be used together with the quadrature touch sensingdescribed in FIGS. 16A-16D.

FIGS. 19A-20B illustrate exemplary timing diagrams for performingacoustic touch and force sensing according to examples of thedisclosure. FIGS. 19A-20B can further be understood in conjunction withthe various examples of circuitry configurations described with regardsto FIGS. 21-27 below. FIGS. 19A and 19B illustrate timing diagrams for asequential acoustic touch and force sensing mode of operation.Specifically, FIGS. 19A and 19B illustrate a frame time 1900 that cancorrespond to a complete sequence of events for a touch and forcesensing operation. In some examples, the frame time 1900 can begin witha touch capture phase 1902 followed by a force capture phase 1904 suchthat the two phases do not overlap in time. In some examples, the forcecapture phase 1904 can be followed by the touch capture phase 1902(e.g., the force capture phase can be performed first). In someexamples, touch capture phase 1902 and force capture phase 1904 can befollowed by a data transfer period 1906 (e.g., transferring measuredtouch and force data to be processed off-chip). In some examples, analgorithm period 1908 can be provided for processing touch and forcedata for an algorithm that can be used to determine information abouttouch location and force based on the data measured during the touchcapture 1902 and force capture 1904. In some examples, the algorithm1908 can be performed on separate circuitry or a processor residing on adifferent chip from the touch and force sense circuitry. In someexamples, the frame time can include an idle period 1910 in which notouch and force measurement, data transfer, or algorithm calculationsare performed. In some examples, the data transfer period 1906, thealgorithm period 1908, or both, can be pipelined or interleaved with thedetection without departing from the scope of the present disclosure. Insome examples, the transducer can be grounded (e.g., by transmittercircuitry that has grounding capability of switches that can selectivelycouple the transducer's electrodes to ground) during the idle period1910. In some examples, the algorithm to analyze the touch and forcedata can be performed on the same chip as acoustic touch/force sensingcircuit used for the touch and force measurements, and algorithm period1908 can come before data transfer period 1906. In such an example, thedata being sent during the data transfer period 1906 after the algorithmperiod can be the algorithm results. Alternatively both the rawmeasurement data and the algorithm results can be transmitted during thedata transfer period 1906 when algorithm period 1908 is performed on thesame circuitry as the touch and force sense circuitry. In some examples,each of touch capture phase 1902 and force capture phase 1904 caninclude driving and sensing a subset of one or more of a group oftransducers. For example, the touch capture phase shows sequentiallyperforming measurements on four transducers, XDUCER1, XDUCER2, XDUCER3,XDUCER 4. These four illustrated transducers can correspond totransducers 502A-502D illustrated in FIG. 5A above. It should beunderstood that the timing diagrams illustrated in FIGS. 19A-19B can beapplied for any number of transducers being used for acoustic touch andforce sensing according to examples of the disclosure. Furthermore, thesequence of the detection from multiple transducers can be arranged in adifferent order from the one illustrated without departing from thescope of the present disclosure. In addition, the sequence of detectionof the multiple transducers can be changed in different frames withoutdeparting from the scope of the present disclosure. In yet otherexamples, a subset of the transducers can be sampled in each framerather than sampling all of the transducers in every frame withoutdeparting from the scope of the present disclosure. FIG. 19A showsmultiple measurements represented by measurement timing slices 1912 thatcan be used to obtain an average value for touch capture and forcecapture. For example, eight touch measurements for XDUCER 1 can beaveraged, followed by eight measurements each for XDUCER2-XDUCER4, andthen similarly eight force measurements of each of XDUCER1-XDUCER4 canbe performed. For example, each measurement timing slice 1912 caninclude a transmit (Tx) function 1914 (e.g., driving a signal onto thetransducer to produce an acoustic wave) and a receive (Rx) function 1916(e.g., receiving reflected signals corresponding to respective touch orforce measurements). In some examples, the transmit (Tx) and receive(Rx) functions can be followed by a pulse ring down period 1918 (e.g.,to allow ringing signals, as described above with reference to FIG. 8A,to stop). In some examples, the pulse ring down period 1918 can preventsuccessive measurements from interfering with each other. FIG. 19Aillustrates eight measurement time slices 1912 for each transducermeasurement averaging operation. However, it should be understood thataveraging can used with a different number of measurements than eight,(e.g., as long as there are two or more measurements to average) withoutdeparting from the scope of the disclosure. Moreover, the number ofmeasurement averages may be different during touch capture phase 1902and force capture phase 1904 (e.g., measurements from the touch capturephase 1902 can be averaged over more measurements than in the forcecapture phase 1904, and vice versa). In some examples, the touch capturephase 1902 can have a longer duration than force capture phase 1904 asillustrated in FIG. 19B. In some examples, the difference in durationsof the touch capture phase 1902 and force capture phase 1904 can relateto the difference in distance that an acoustic wave travels in the touchphase 1902 (e.g., across the cover glass 601 or 611 above) as comparedto the distance that an acoustic wave travels in the force phase 1904(e.g., through the thickness of deformable material 604 or 614 above).To illustrate this point, FIG. 19B illustrates an exemplary timingdiagram where the respective receive durations (Rx1-RxN) for the forcephase 1904 measurements are shorter than the respective receive duration(Rx1-RxN) for the touch phase 1902 measurements as described immediatelyabove. As a result, FIG. 19B illustrates that the total duration for theforce phase 1904 can be shorter than the total duration of the touchphase 1902 even when the same total numbers of transmit and receives areperformed during each phase. It should be understood that the durationof various phases illustrated in the timing diagrams of FIGS. 19A-19B,e.g., touch capture 1902, force capture 1904, data transfer 1906,algorithm 1908, idle 1910, etc. are not necessarily drawn to scale andare provided for the purposes of illustration.

In some examples, force detections for each of the transducersXDUCER1-XDUCER4 can be performed simultaneously to reduce the totalduration of force measurements during the force phase 1904. In such anexample, each transducer XDUCER1-XDUCER4 can be provided with a transmitcircuit to drive the transducer and an analog front end to receive theforce measurement signals (e.g., from reflections in the deformablematerial 604 or 614 above coupled to each individual transducer e.g.,502A-502D above). In some examples, a single transmit circuit can beused to sequentially drive each individual transducer XDUCER1-XDUCER4with a slight time delay between driving each transducer, and thensimultaneously capture the force measurement signals at four analogfront ends from each of the transducers XDUCER1-XDUCER4 to reduce thetime for force detection.

FIGS. 20A and 20B illustrate timing diagrams for a combined acoustictouch and force sensing mode of operation. Specifically, in contrast tothe mode of operation illustrated in FIGS. 19A-19B, in the mode ofoperation illustrated in FIGS. 20A and 20B, the touch and force capturephases are combined into a touch and force capture phase 2020. This canbe accomplished by performing a force receive function 2022 and a touchreceive function 2024 as illustrated in FIG. 20B during a singlecombined Rx function 2016. In some examples, the force and touch receivefunctions can both be performed sequentially after a single transmit(Tx) function 2014 because reflections associated with force measurementcan arrive at the transducer and any ringing associated with the forcemeasurement can settle before any reflections associated with touchmeasurement are received at the transducer (e.g., as described withreference to FIG. 7 above). In some examples, the timing illustrated inFIGS. 20A and 20B can most preferably be used when signals for the forcesensing occur during a dead zone for touch signals from touch sensing.For example, if reflections in a deformable material (e.g., 604 or 614above) used for force sensing are sufficiently attenuated beforereflected touch measurement signals can return to the transducer, thenthe two operations can be performed sequentially based on a single Txfunction 2014. In other words, depending on the geometries and materialproperties of the deformable materials (e.g., 604 or 614 above) andcover glass (e.g., 601 and 611 above), the signals for touch capture andforce capture can be temporally isolated in two distinct time windows(e.g., force receive 2022 and touch receive 2024) following a singletransmit Tx function 2014. Similar to the description of FIG. 19A-19Babove, the frame time shown in FIGS. 20A-20B can include data transferperiod 2006, algorithm period 2008, and idle period 2010. As notedabove, in some examples, the data transfer period 2006, the algorithmperiod 2008, or both, can be pipelined or interleaved with the touch andforce detection without departing from the scope of the presentdisclosure. Similar to the description of FIG. 19A above, FIG. 20A showsthat averaging can be performed for the combined touch and forcecaptures 2020 as illustrated by measurement time slices 2012.Furthermore, the sequence of the detection from multiple transducers(e.g., XDUCER1, XDUCER2, XDUCER3, and XDUCER4) can be arranged in adifferent order from the one illustrated without departing from thescope of the present disclosure. In addition the sequence of detectionof the multiple transducers can be changed in different frames withoutdeparting from the scope of the present disclosure. In yet otherexamples, a subset of the transducers can be sampled in each framerather than sampling all of the transducers in every frame withoutdeparting from the scope of the present disclosure. As shown in FIG.20B, receive period 2016 can include both a force receive 2022 and atouch receive 2024. As should be understood from the disclosure above,respective force measurements 2024 can be averaged together andrespective touch measurements 2022 can also be averaged together. Itshould be understood that the duration of various phases illustrated inthe timing diagrams of FIGS. 20A-20B, e.g., touch and force capture2020, data transfer 2006, algorithm 2008, idle 2010, etc. are notnecessarily drawn to scale and are provided for the purposes ofillustration.

FIG. 21 illustrates an exemplary switching configuration 2100 for anacoustic touch and force sensing system according to examples of thedisclosure. Transducer 2102 can include a pair of electrodes (e.g.,electrodes 2104 and 2106) disposed on opposing sides of the transducerthat can be used to both drive transducer 2102 and to receive electricalsignals generated by transducer 2102 (e.g., in response to a receivedacoustic signal). In some examples, one of the two electrodes can act asa common electrode (e.g., electrode 2106), and the second of the twoelectrodes can act as both the drive and sense electrode (e.g.,electrode 2104) for the transducer. In some examples, a differentialdrive and sense scheme can be used by differential driving electrodes2014 and 2016 and differentially receiving from electrodes 2014 and2016. Electrode 2104 and electrode 2106 can be connected to touch andforce control and readout circuitry 2108 for acoustic touch and forcesensing. Touch and force control and readout circuitry 2108 can includeanalog front end (AFE) amplifier 2112, the output of which can beconnected to sense circuitry 2110. Outputs from sense circuitry 2110 canbe connected to the inputs of transmitter 2114. In some examples,electrode 2104 and electrode 2106 can be connected to the inputterminals of AFE amplifier 2112 via switches 21S1 and 21S2, respectively(as indicated by connection labels 21A and 21B). In addition, electrode2104 and electrode 2106 can be connected to the outputs of transmitter2114 via switches 21S3 and 21S4, respectively (as also indicated byconnection labels 21A and 21B). During a receive (Rx) function, switches21S1 and 21S2 can be closed, and switches 21S3 and 21S4 can be open. Theswitch configuration during the Rx function can allow the AFE 2112 toreceive electrical signals from the electrodes 2104 and 2106 oftransducer 2102. During a transmit (Tx) function switches 21S3 and 21S4can be closed, and switches 21S1 and 21S2 can be open. The switchconfiguration during the Tx function can allow transmitter 2114 to drivethe electrodes 2104 and 2106 of transducer 2102 to generate an acousticwave. Notably, exemplary switching configuration 2100 is compatible withthe modes of operation illustrated in FIGS. 19A-20B. In some examples,sense circuitry 2110 can include one or more of digital-to-analogconverters (DAC) 402A, filter 402B, gain and offset correction circuit412, demodulation circuit 414, filter 416, analog-to-digital converter(ADC) 418, input/output (I/O) circuit 420, acoustic scan control circuit422, force detection circuit 424, processor SoC 430, host processor 432,auxiliary processor 434, and/or any other sense circuitry describedabove with reference to FIG. 4. In some examples, sense circuitry 2110can be on a different chip from the AFE 2112, transmitter 2114, andswitches 21S1-21S4. In some examples, inputs of AFE amplifier 2112 canbe connected to a first transducer for receiving, and the outputs oftransmitter 2114 can be connected to a second transducer, different thanthe first transducer, for transmitting. In some examples, the touch andforce control and readout 2108 can be included on a silicon chip. Insome examples, the transmit circuitry can be designed to drive highervoltages (or currents) to produce sufficient motion in the transducer togenerate an acoustic wave in the surface of a device, and the receivecircuitry can be designed for receiving smaller amplitude reflectedenergy. Accordingly, in some examples, the transmit circuitry andreceive circuitry can be included on different silicon chips to avoidinterference with the operation of the receive circuitry by the transmitcircuitry.

FIG. 22 illustrates an exemplary switching configuration 2200 for anacoustic touch and force sensing system according to examples of thedisclosure. Transducer 2202 can include a pair of electrodes (e.g.,electrodes 2204A and 2204B) disposed on one side of the transducer and asecond electrode (e.g., common electrode 2206) disposed on the oppositeside of the transducer. In some examples, the electrode configuration oftransducer 2202 can correspond to the electrode configurationillustrated in FIGS. 10A-10B and 11A above. Electrodes 2204A, 2204B, and2206 can be connected to touch and force control and readout circuitry2208 for acoustic touch and force sensing. Touch and force control andreadout circuitry 2208 can include analog front end (AFE) amplifier2212, the output of which can be connected to sense circuitry 2210.Outputs from sense circuitry 2210 can be connected to the inputs oftransmitter 2214. In some examples, electrodes 2204A and 2204B can beconnected to the input terminals of AFE amplifier 2212 via switches 22S1and 22S2, respectively (as indicated by connection labels 22A and 22B).In addition, electrode 2204A, electrode 2204B, and electrode 2206 can beconnected to the outputs of transmitter 2214 via switches 22S3, 23S4,and 22S5, respectively (as indicated by connection labels 22A, 22B, and22C). In the illustrated configuration, electrode 2204A and electrode2204B (both on the same side of transducer 2302) can be connected fromthe same output terminal of transmitter 2214 (as indicated by connectionlabels 22A and 22B). During a receive (Rx) function, switches 2251 and22S2 can be closed, and switches 22S3, 22S4, and 22S5 can be open. Insome examples, electrode 2206 can be left floating by the switchconfiguration during the Rx function, which can correspond to the analogcommon mode rejection described in FIGS. 14A-14C above. The switchconfiguration during the Rx function can allow the AFE 2212 to receiveelectrical signals from the electrodes 2204A and 2204B of transducer2202. During a transmit (Tx) function switches 22S3, 22S4, and 22S5 canbe closed, and switches 2251 and 22S2 can be open. The switchconfiguration during the Tx function can allow transmitter 2214 to drivethe electrodes 2204A, 2204B, and 2206 of transducer 2202 to create apotential across the transducer and generate an acoustic wave. Notably,exemplary switching configuration 2200 is compatible with the modes ofoperation illustrated in FIGS. 19A-20B. In some examples, sensecircuitry 2210 can include one or more of digital-to-analog converters(DAC) 402A, filter 402B, gain and offset correction circuit 412,demodulation circuit 414, filter 416, analog-to-digital converter (ADC)418, input/output (I/O) circuit 420, acoustic scan control circuit 422,force detection circuit 424, processor SoC 430, host processor 432,auxiliary processor 434, and/or any other sense circuitry describedabove with reference to FIG. 4. In some examples, sense circuitry 2210can be on a different chip from AFE 2212, transmitter 2214, and switches22S1-22S5. In some examples, inputs of AFE amplifier 2212 can beconnected to a first transducer for receiving, and the outputs oftransmitter 2214 can be connected to a second transducer, different thanthe first transducer, for transmitting. In some examples, the touch andforce control and readout circuitry 2208 can be included on a siliconchip. In some examples, the transmit circuitry can be designed to drivehigher voltages (or currents) to produce sufficient motion in thetransducer to generate an acoustic wave in the surface of a device, andthe receive circuitry can be designed for receiving smaller amplitudereflected energy. Accordingly, in some examples, transmit circuitry andreceive circuitry can be included on different silicon chips to avoidinterference with the operation of the receive circuitry by the transmitcircuitry.

FIG. 23 illustrates an exemplary switching configuration 2300 for anacoustic touch and force sensing system according to examples of thedisclosure. Transducer 2302 can include a pair of electrodes (e.g.,electrodes 2304A and 2304B) disposed on one side of the transducer and asecond electrode (e.g., common electrode 2306) disposed on the oppositeside of the transducer. In some examples, the electrode configuration oftransducer 2302 can correspond to the electrode configurationillustrated in FIGS. 10A-10B and 11A above. Electrodes 2304A, 2304B, and2306 can be connected to touch and force control and readout circuitry2308 for acoustic touch and force sensing. Touch and force control andreadout circuitry 2308 can include analog front end (AFE) amplifiers2312 and 2314, the output of which can be connected to sense circuitry2310. Outputs from sense circuitry 2310 can be connected to the inputsof transmitter 2316. In some examples, electrodes 2304A and electrode2306 can be connected to the input terminals of AFE amplifier 2312 viaswitches 23S1 and 23S2, respectively (as indicated by connection labels23A and 23C); and electrodes 2304B and electrode 2306 can be connectedto the input terminals of AFE amplifier 2314 via switches 23S3 and 23S4,respectively (as indicated by connection labels 23B and 23C). Inaddition, electrodes 2304A, electrodes 2304B, and electrode 2306 can beconnected to the outputs of transmitter 2316 via switches 23S5, 23S6,and 23S7, respectively (as indicated by connection labels 23A, 23B, and23C). It should be understood that, while not illustrated, electrodes2304A and 2304B can represent electrode configurations as describedabove with reference to FIGS. 9-14. In the illustrated configuration,electrodes 2304A and electrodes 2304B can be connected from the sameoutput terminal of transmitter 2316 (as indicated by connection labels23A and 23B). During a receive (Rx) function, switches 23S1, 23S2, 23S3,23S4, and 23S7 can be closed, and switches 23 S5 and 23 S6 can be open.The switch configuration during the Rx function can allow the AFE 2212to receive electrical signals from the electrodes 2304A, 2304B, and 2306of transducer 2302, and allow transmitter 2316 to drive electrode 2306of transducer 2302 to ground or another reference potential.Accordingly, unlike the configuration in FIG. 22, each of the electrodes2304A and 2304B in FIG. 23 can be read with a common mode signalcomponent included in the measured signal. In some examples, the commonmode component can be removed in the digital domain. During a transmit(Tx) function switches 23S5, 23S6, and 23S7 can be closed, and switches23S1, 23S2, 23S3, and 23S4 can be open. The switch configuration duringthe Tx function can allow transmitter 2214 to drive the electrodes2304A, 2304B, and 2306 of transducer 2302 to create a potential acrossthe transducer and generate an acoustic wave. In some examples, theoutput of switch 23S7 can be tied to ground (e.g., common electrode 2306can be tied to ground as described above with reference to FIG. 14A).Notably, exemplary switching configuration 2300 is compatible with themodes of operation illustrated in FIGS. 19A-20B. In some examples, sensecircuitry 2310 can include one or more of digital-to-analog converters(DAC) 402A, filter 402B, gain and offset correction circuit 412,demodulation circuit 414, filter 416, analog-to-digital converter (ADC)418, input/output (I/O) circuit 420, acoustic scan control circuit 422,force detection circuit 424, processor SoC 430, host processor 432,auxiliary processor 434, and/or any other sense circuitry describedabove with reference to FIG. 4. In some examples, sense circuitry 2310can be on a different chip from AFE 2312, AFE 2314, transmitter 2316,and switches 23S1-23S7. In some examples, inputs of AFE amplifiers 2312and 2314 can be connected to a first transducer for receiving, and theoutputs of transmitter 2316 can be connected to a second transducer,different than the first transducer, for transmitting. In some examples,the touch and force control and readout circuitry 2308 can be includedon a silicon chip. In some examples, the transmit circuitry can bedesigned to drive higher voltages (or currents) to produce sufficientmotion in the transducer to generate an acoustic wave in the surface ofa device, and the receive circuitry can be designed for receivingsmaller amplitude reflected energy. Accordingly, in some examples, thetransmit circuitry and receive circuitry can be included on differentsilicon chips to avoid interference with the operation of the receivecircuitry by the transmit circuitry.

FIG. 24 illustrates an exemplary switching configuration 2400 for anacoustic touch and force sensing system according to examples of thedisclosure. Transducer 2402 can include two sets of two electrodedifferential patterns, electrodes 2404A and 2404B on a first side of thetransducer and electrodes 2406C and 2406D on a second side of thetransducer. As illustrated, the first side electrodes 2404A can beconnected (as indicated by connection label 24A), and first sideelectrodes 2404B can be connected (as indicated by connection label24B). It should be understood that, electrodes 2404A, 2404B, 2406C, and2406D can correspond to the electrode configuration illustrated in FIG.13A. It should also be understood that the switching scheme illustratedin FIG. 24 can be adapted for different numbers of electrodes onopposing sides of the transducer without departing from the scope of thepresent disclosure. As illustrated electrodes 2406C/2406D can have alarger electrode size and a corresponding larger electrode pitch,leading each of the electrode pairs to have a different correspondingspatial frequency as described and illustrated in FIGS. 13A and 13B. Insome examples, the spatial frequencies corresponding to electrodes2404A/2404B can be higher than the spatial frequencies correspondingelectrodes 2406C/2406D. Electrodes 2404A, 2404B, 2406C, and 2406D can beconnected to touch and force control and readout circuitry 2408 foracoustic touch and force sensing. Touch and force control and readoutcircuitry 2408 can include analog front end (AFE) amplifier 2412, theoutput of which can be connected to sense circuitry 2410. Outputs fromsense circuitry 2410 can be connected to the inputs of transmitter 2414.In some examples, electrodes 2404A and electrode 2406C can both beconnected to a first input terminal of AFE amplifier 2412 via switches24S1 and 24S2, respectively (as indicated by connection labels 2404A and24C). Electrodes 2404B and electrode 2406D can both be connected to asecond input terminal of AFE amplifier 2412 via switches 24S3 and 24S4,respectively (as indicated by connection labels 24B and 24D). Inaddition, electrodes 2404A and electrodes 2404B can both be connected toa first output terminal of transmitter 2414 via switches 24S5 and 24S6,respectively (as indicated by connection labels 24A and 24B). Electrodes2406C and electrodes 2406D can both be connected to a second outputterminal of transmitter 2414 via switches 24S7 and 24S8, respectively(as indicated by connection labels 24C and 24D). During a touch receive(Rx) function, switches 24S1 and 24S3 can be closed, and switches 24S2,24S4, 24S5, 24S6, 24S7, and 24S8 can be open. The switch configurationduring the touch Rx function can allow the AFE 2412 to receiveelectrical signals from the electrodes 2404A and 2406B of transducer2402. At the same time, electrodes 2406C and 2406D can be left floatingfor accomplishing a common mode rejection function as described withregard to FIGS. 14A-14C above. During a force receive (Rx) function,switches 24S2 and 24S4 can be closed, and switches 24S1, 24S3, 24S5,24S6, 24S7, and 24S8 can be open. The switch configuration during theforce Rx function can allow the AFE 2412 to receive electrical signalsfrom the electrodes 2406C and 2406D of transducer 2402. At the sametime, electrodes 2406A and 2406B can be left floating for accomplishinga common mode rejection function as described with regard to FIGS.14A-14C above. During a transmit (Tx) function switches 24S5, 24S6,24S7, and 24S8 can be closed, and switches 24S1, 24S2, 24S3, and 24S4can be open. The switch configuration during the Tx function can allowtransmitter 2414 to drive the electrodes 2404A and 2404B (one a firstside of the transducer 2402) and electrodes 2406C and 2406D (on theopposite side of transducer 2402) to create a potential across thetransducer and generate an acoustic wave. Notably, exemplary switchingconfiguration 2400 is compatible with the modes of operation illustratedin FIGS. 19A-20B. In some examples, sense circuitry 2410 can include oneor more of digital-to-analog converters (DAC) 402A, filter 402B, gainand offset correction circuit 412, demodulation circuit 414, filter 416,analog-to-digital converter (ADC) 418, input/output (I/O) circuit 420,acoustic scan control circuit 422, force detection circuit 424,processor SoC 430, host processor 432, auxiliary processor 434, and/orany other sense circuitry described above with reference to FIG. 4. Insome examples, sense circuitry 2410 can be on a different chip from AFE2412, transmitter 2414, and switches 24S1-24S8. In some examples, inputsof AFE amplifier 2412 can be connected to a first transducer forreceiving, and the outputs of transmitter 2414 can be connected to asecond transducer, different than the first transducer, fortransmitting. In some examples, the touch and force control and readoutcircuitry 2408 can be included on a silicon chip. In some examples, thetransmit circuitry can be designed to drive higher voltages (orcurrents) to produce sufficient motion in the transducer to generate anacoustic wave in the surface of a device, and the receive circuitry canbe designed for receiving smaller amplitude reflected energy.Accordingly, in some examples, the transmit circuitry and receivecircuitry can be included on different silicon chips to avoidinterference with the operation of the receive circuitry by the transmitcircuitry.

FIG. 25 illustrates an exemplary switching configuration 2500 for anacoustic touch and force sensing system according to examples of thedisclosure. Transducer 2502 can include a four spatial differentialelectrode configuration with electrodes 2504A-2504D disposed on a firstside of the transducer and common electrode 2406 disposed on a secondside of the transducer. It should be recognizable that the four spatialdifferential electrode configuration illustrated in FIG. 25 cancorrespond to the configuration described above with reference to FIG.11B. Electrodes 2504A, 2504B, 2504C, 2504D, and 2506 can be connected totouch and force control and readout circuitry 2508 for acoustic touchand force sensing. Touch and force control and readout circuitry 2508can include analog front end (AFE) amplifier 2512, the output of whichcan be connected to sense circuitry 2510. Outputs from sense circuitry2510 can be connected to the inputs of transmitter 2514. In someexamples, electrodes 2504A, 2504B, and 2504C can be connected to a firstinput terminal of AFE amplifier 2512 via switches 25S1, 25S2, and 25S3,respectively (as indicated by connection labels 25A-25C). Electrodes2504B, 2504C, and 2504D can be connected to a second input terminal ofAFE amplifier 2512 via switches 25S4, 25S5, and 25S6, respectively (asindicated by connection labels 25B-25D). In addition, electrodes 2504A,2504B, 2504C, and 2504D can be connected to a first output terminal oftransmitter 2514 via switches 25S7, 25S8, 25S9, and 25S10, respectively(as indicated by connection labels 25A-25D). Electrode 2506 can beconnected to a second output terminal of transmitter 2514 via switch25S11 (as indicated by connection label 25E). It should be understoodthat the switch scheme of FIG. 25 can be adapted to different electrodeconfigurations, including those disclosed in FIGS. 13A-13B, withoutdeparting from the scope of the present disclosure. During a receive(Rx) touch function, switches 25S1, 25S3, 25S4, and 25S6 can be closed,and switches 25S2, 25S5, 25S7, 25S8, 25S9, 25S10, and 25S11 can be open.The switch configuration during the touch Rx function can allow the AFE2512 to receive electrical signals from the electrodes 2504A and 2504Cat a first terminal of AFE 2512 and to receive electrical signals fromelectrodes 2504B and 2504D at a second terminal of AFE 2512. In thetouch measurement mode, differential measurements are thus taken betweenadjacent electrodes, which can correspond to a first spatial frequency.During a force receive (Rx) function, switches 25S1, 25S2, 25S5, and25S6 can be closed, and switches 25S3, 25S4, 25S7, 25S8, 25S9, 25S10,and 25S11 can be open. The switch configuration during the force Rxfunction can allow the AFE 2512 to receive electrical signals from theelectrodes 2504A and 2504B at a first terminal of AFE 2512 and toreceive electrical signals from electrodes 2504C and 2504D at a secondterminal of AFE 2512. In some examples, in the force Rx configuration,the electrodes can be measured with a lower pitch because differentialmeasurements are taken between adjacent pairs of electrodes rather thanadjacent individual electrodes as shown in the touch Rx configurationabove. Thus, the differential measurements in the force Rx configurationcan correspond to a second spatial frequency lower than the firstspatial frequency. It should be also understood using a lower spatialfrequency for the touch Rx and higher spatial frequency for force Rx canalso be done without departing from the scope of the present disclosure.In both the force Rx and touch Rx configurations described above,electrodes 2506 can be left floating for accomplishing a common moderejection function as described with regard to FIGS. 14A-14C above.During a transmit (Tx) function switches 25S7, 25S8, 25S9, 25S10, and25S11 can be closed, and switches 25S1, 25S2, 25S3, 25S4, 25S5, and 25S6can be open. The switch configuration during the Tx function can allowtransmitter 2514 to drive the electrodes 2504A, 2504B, 2504C, 2504D, and2206 of transducer 2502 to create a potential across the transducer andgenerate an acoustic wave. Notably, exemplary switching configuration2500 is compatible with the modes of operation illustrated in FIGS.19A-20B. In some examples, sense circuitry 2510 can include one or moreof digital-to-analog converters (DAC) 402A, filter 402B, gain and offsetcorrection circuit 412, demodulation circuit 414, filter 416,analog-to-digital converter (ADC) 418, input/output (I/O) circuit 420,acoustic scan control circuit 422, force detection circuit 424,processor SoC 430, host processor 432, auxiliary processor 434, and/orany other sense circuitry described above with reference to FIG. 4. Insome examples, sense circuitry 2510 can be on a different chip from AFE2512, transmitter 2514, and switches 25S1-25S11. In some examples,inputs of AFE amplifier 2512 can be connected to a first transducer forreceiving, and the outputs of transmitter 2514 can be connected to asecond transducer, different than the first transducer, fortransmitting. In some examples, the touch and force control and readoutcircuitry 2508 can be included on a silicon chip. In some examples, thetransmit circuitry can be designed to drive higher voltages (orcurrents) to produce sufficient motion in the transducer to generate anacoustic wave in the surface of a device, and the receive circuitry canbe designed for receiving smaller amplitude reflected energy.Accordingly, in some examples, the transmit circuitry and receivecircuitry can be included on different silicon chips to avoidinterference with the operation of the receive circuitry by the transmitcircuitry. In some examples, each of the four electrodes 2504A, 2504B,2504C, and 2504D can be separately read by four analog front ends (e.g.,as illustrated and described in more detail with regard to FIGS. 31A-31Bbelow) to simultaneously measure the signals of each of the fourelectrodes.

FIG. 26 illustrates an exemplary switching configuration 2600 for anacoustic touch and force sensing system according to examples of thedisclosure. Transducer 2602 can include two sets of two electrodedifferential patterns, electrodes 2604A and 2604B on a first side of thetransducer, and electrodes 2606C and 2606D on a second side of thetransducer. As illustrated, the first side electrodes 2604A can beconnected (as indicated by connection label 26A), and first sideelectrodes 2604B can be connected (as indicated by connection label26B). It should be understood that the switch scheme of FIG. 25 can beadapted to different electrode configurations, including those disclosedin FIGS. 13A-13B, without departing from the scope of the presentdisclosure. As illustrated electrodes 2606C/2606D can have a largerelectrode size and a corresponding larger electrode pitch, leading eachof the electrode pairs to have a different corresponding spatialfrequencies. In some examples, the spatial frequencies corresponding toelectrodes 2604A/2604B can be higher than the spatial frequencycorresponding to electrodes 2606C/2606D as illustrated in FIGS. 13A and13B above. Electrodes 2604A, 2604B, 2606C, and 2606D can be connected totouch and force control and readout circuitry 2608 for acoustic touchand force sensing. Touch and force control and readout circuitry 2608can include analog front end (AFE) amplifiers 2612 and 2614, the outputof which can be connected to sense circuitry 2610. Outputs from sensecircuitry 2610 can be connected to the inputs of transmitter 2616. Insome examples, electrodes 2604A and 2604B can be connected to the inputterminals of AFE amplifier 2612 via switches 26S1 and 26S2, respectively(as indicated by connection labels 26A-26B), and the outputs ofelectrodes 2604C and 2604D can be connected to the input terminals ofAFE amplifier 2614 via switches 26S3 and 26S4, respectively (asindicated by connection labels 26C-26D). In addition, electrodes 2604A,2604B, 2606C, and 2606D can be connected to the outputs of transmitter2616 via switches 26S5, 26S6, 26S7, and 26S8, respectively (as indicatedby connection labels 26A-26D). In the illustrated configuration,electrodes 2604A and 2604B can be connected from the same outputterminal of transmitter 2616 (e.g., a first terminal) (as indicated byconnection labels 26A-26B). In the illustrated configuration, electrodes2606C and 2606D can be connected from the same output terminal oftransmitter 2616 (e.g., a second terminal, different from the firstterminal) (as indicated by connection labels 26C-26D). During a touchreceive (Rx) function, switches 26S1 and 26S2 can be closed, andswitches 26S3, 26S4, 26S5, 26S6, 26S7, and 26S8 can be open. The switchconfiguration during the touch Rx function can allow the touch AFE 2612to receive electrical signals from the electrodes 2604A and 2604B oftransducer 2602. During a force receive (Rx) function, switches 26S3 and26S4 can be closed, and switches 26S1, 26S2, 26S5, 26S6, 26S7, and 26S8can be open. The switch configuration during the force Rx function canallow the force AFE 2614 to receive electrical signals from theelectrodes 2606C and 2606D of transducer 2602. As mentioned in variousexamples above, the electrodes that are not being read (e.g., 2606C and2606D during the touch Rx and 2606A and 2606B during the force Rx) canbe left floating to allow for common mode rejection as described abovewith regard to FIGS. 14A-14C. During a transmit (Tx) function switches26S5, 26S6, 26S7, and 26S8 can be closed, and switches 26S1, 26S2, 26S3,and 26S4 can be open. The switch configuration during the Tx functioncan allow transmitter 2616 to drive the electrodes 2604A, 2604B, 2606C,and 2606D of transducer 2602 to create a potential across the transducer2602 and generate an acoustic wave. Notably, exemplary switchingconfiguration 2600 is compatible with the modes of operation illustratedin FIGS. 19A-20B. In some examples, sense circuitry 2610 can include oneor more of digital-to-analog converters (DAC) 402A, filter 402B, gainand offset correction circuit 412, demodulation circuit 414, filter 416,analog-to-digital converter (ADC) 418, input/output (I/O) circuit 420,acoustic scan control circuit 422, force detection circuit 424,processor SoC 430, host processor 432, auxiliary processor 434, and/orany other sense circuitry described above with reference to FIG. 4. Insome examples, sense circuitry 2610 can be on a different chip fromtouch AFE 2612, AFE2614, transmitter 2616, and switches 26S1-21S8. Insome examples, inputs of AFE amplifiers 2612 and 2614 can be connectedto a first transducer for receiving, and the outputs of transmitter 2616can be connected to a second transducer, different than the firsttransducer, for transmitting. In some examples, the touch and forcecontrol and readout circuitry 2608 can be included on a silicon chip. Insome examples, the transmit circuitry can be designed to drive highervoltages (or currents) to produce sufficient motion in the transducer togenerate an acoustic wave in the surface of a device, and the receivecircuitry can be designed for receiving smaller amplitude reflectedenergy. Accordingly, in some examples, the transmit circuitry andreceive circuitry can be included on different silicon chips to avoidinterference with the operation of the receive circuitry by the transmitcircuitry.

FIG. 27 illustrates an exemplary switching configuration 2700 for anacoustic touch and force sensing system according to examples of thedisclosure. Transducer 2702 can include two sets of two electrodedifferential patterns, electrodes 2704A and 2704B on a first side of thetransducer, and electrodes 2706C and 2706D on a second side of thetransducer. As illustrated, the first side electrodes 2704A can beconnected (as indicated by connection label 27A), and first sideelectrodes 2704B can be connected (as indicated by connection label27B). It should be understood that, while not illustrated, electrodes2704A, 2704B, 2706C, and 2706D can represent electrode configurations asdescribed above with reference to FIGS. 9-14. As illustrated electrodes2706C/2706D can have a larger electrode size and a corresponding largerelectrode pitch, leading each of the electrode pairs to have a differentcorresponding spatial frequency. In some examples, the spatialfrequencies corresponding to electrodes 2704A/2704B can be higher thanthe spatial frequency corresponding to electrodes 2706C/2706D.Electrodes 2704A, 2704B, 2706C, and 2706D can be connected to touch andforce control and readout circuitry 2708 for acoustic touch and forcesensing. Touch and force control and readout circuitry 2708 can includeanalog front end (AFE) amplifiers 2712 and 2714, the output of which canbe connected to sense circuitry 2710. The output of sense circuitry 2710can be connected to the inputs of transmitter 2716. In some examples,electrodes 2704A and 2704C can be connected to the input terminals ofAFE amplifier 2712 via switches 27S1 and 27S2, respectively (asindicated by connection labels 27A and 27C), and electrodes 2704B and2704D can be connected to the input terminals of AFE amplifier 2714 viaswitches 27S3 and 27S4, respectively (as indicated by connection labels27B and 27D). In addition, electrodes 2704A, 2704B, 2706C, and 2706D canbe connected to the outputs of transmitter 2716 via switches 27S5, 27S6,27S7, and 27S8, respectively (as indicated by connection labels27A-27D). It should be understood that, while not illustrated,electrodes 2704A and 2704B can represent electrode configurations asdescribed above with reference to FIGS. 9-14. In the illustratedconfiguration, electrodes 2704A and 2704B can be connected from the sameoutput terminal of transmitter 2716 (e.g., a first terminal) (asindicated by connection labels 27A-27B). In the illustratedconfiguration, electrodes 2706C and 2706D can be connected from the sameoutput terminal of transmitter 2716 (e.g., a second terminal, differentfrom the first terminal) (as indicated by connection labels 27C-27D).During a touch receive (Rx) function, switches 27S1, 27S2, 27S3, 27S4,27S7, and 27S8 can be closed, and switches 27S5 and 27S6 can be open.The switch configuration during the touch Rx function can allow the AFE2712 to receive electrical signals from the electrodes 2704A and 2706Cof transducer 2702, AFE 2714 to receive electrical signals from theelectrodes 2704B and 2706D of transducer 2702, and transmitter 2716 todrive the electrodes 2706C and 2706D with a ground or referencepotential for single ended measurement of electrodes 2706A and 2706B.During a force receive (Rx) function, switches 27S1, 27S2, 27S3, 27S4,27S5, and 27S6 can be closed, and switches 27S7 and 27S8 can be open.The switch configuration during the force Rx function can allow the AFE2714 to receive electrical signals from the electrodes 2704B and 2706Dof transducer 2702, AFE 2714 to receive electrical signals from theelectrodes 2704B and 2706D of transducer 2702, and transmitter 2716 todrive the electrodes 2704A and 2704B of transducer 2702 with ground oranother reference potential for single ended measurement of electrodes2704C and 2704D. During a transmit (Tx) function switches 27S5, 27S6,27S7, and 27S8 can be closed, and switches 27S1, 27S2, 27S3, and 27S4can be open. The switch configuration during the Tx function can allowtransmitter 2716 to drive the electrodes 2704A, 2704B, 2706C, and 2706Dof transducer 2702 to create ane electric potential across thetransducer 2702 and generate an acoustic wave. Notably, exemplaryswitching configuration 2700 is compatible with the modes of operationillustrated in FIGS. 19A-20B. In some examples, sense circuitry 2710 caninclude one or more of digital-to-analog converters (DAC) 402A, filter402B, gain and offset correction circuit 412, demodulation circuit 414,filter 416, analog-to-digital converter (ADC) 418, input/output (I/O)circuit 420, acoustic scan control circuit 422, force detection circuit424, processor SoC 430, host processor 432, auxiliary processor 434,and/or any other sense circuitry described above with reference to FIG.4. In some examples, sense circuitry 2710 can be on a different chipfrom AFE 2712, AFE 2714, transmitter 2716, and switches 27S1-27S8. Insome examples, inputs of AFE amplifiers 2712 and 2714 can be connectedto a first transducer for receiving, and the outputs of transmitter 2716can be connected to a second transducer, different than the firsttransducer, for transmitting. In some examples, the touch and forcecontrol and readout circuitry 2708 can be included on a silicon chip. Insome examples, the transmit circuitry can be designed to drive highervoltages (or currents) to produce sufficient motion in the transducer togenerate an acoustic wave in the surface of a device, and the receivecircuitry can be designed for receiving smaller amplitude reflectedenergy. Accordingly, in some examples, the transmit circuitry andreceive circuitry can be included on different silicon chips to avoidinterference with the operation of the receive circuitry by the transmitcircuitry.

It should be understood that the common electrode described above withreference to FIGS. 21-23 and 25 (e.g., electrodes 2106, 2206, 2306, and2506, respectively) can be floating during the receive (Rx) function tocancel out common mode signals (e.g., as described above with referenceto electrode 1407 of FIGS. 14B and 14C).

FIGS. 28A-30B illustrate exemplary timing diagrams for acoustic touchand force sensing according to examples of the disclosure. As will bediscussed in further detail below, the timing diagrams 29A-29B and30A-30B below closely resemble the timing diagrams 19A-19B and 20A-20Babove, respectively. The main difference between these diagrams is thatthe following timing diagrams are presented with quadrature spatialdifferential sensing in mind as described with regard to FIGS. 15A-18Cabove, where each touch Rx function includes a measurement of anin-phase touch measurement, and a quadrature touch measurement that canbe used to overcome spatial nulls in acoustic differential sensing asdescribed in detail in the disclosure above.

FIGS. 28A and 28B illustrate exemplary timing diagrams for a quadratureacoustic touch and force sensing mode of operation. Specifically, inthis mode of operation the touch and force capture phases are combined.In other words, force and touch receive (Rx) functions 2816 can beperformed simultaneously (e.g., not sequentially as described withreference to FIGS. 19A-20B above). This can be accomplished by includingan analog front end (AFE) amplifier for each sensing electrode in anacoustic touch and force sensing system (e.g., as described in furtherdetail below with reference to FIGS. 31A and 31B). These simultaneousforce and touch receive (Rx) functions 2816 can be performed after asingle transmit (Tx) function 2814. Because force and touch receive (Rx)functions 2816 can be performed simultaneously, the duration of a touchand force capture 2820 in any given frame can be shorter in durationthan in the touch and force sensing modes illustrated in FIGS. 19A-20B.It should be understood that the duration of functions illustrated inthe timing diagrams (e.g., data transfer 2808) are not necessarily drawnto scale. It should be understood that the duration of various phasesillustrated in the timing diagrams of FIGS. 28A-28B, e.g., touch andforce capture 2820, data transfer 2806, algorithm 2808, idle 2810, etc.are not necessarily drawn to scale and are provided for the purposes ofillustration. In some examples, the data transfer period 2806, thealgorithm period 2808, or both, can be pipelined or interleaved with thedetection without departing from the scope of the present disclosure.

FIGS. 29A and 29B illustrate timing diagrams for a quadrature acoustictouch and force sensing mode of operation. Specifically, FIGS. 29A and29B illustrate a touch capture phase 2902 followed by a force capturephase 2904 such that the two phases do not overlap in time. In someexamples, the force capture phase 2904 can be followed by the touchcapture phase 2902 (e.g., the force capture phase can be performedfirst). In some examples, the force capture phase 2904 can be shorter induration than the touch capture phase 2902. As described above withregard to FIGS. 19A-19B each of touch capture phase 2902 and forcecapture phase 2904 can include multiple measurement time slices 2912that can be used to obtain multiple repeated measurements for averaging.For example, each measurement timing slice 2912 can include a transmit(Tx) function 2914 (e.g., driving a signal onto the transducer toproduce an acoustic wave) and a receive (Rx) function 2916 (e.g.,receiving reflected signals corresponding to respective touch or forcemeasurements). As will be described in more detail below regarding FIGS.32-34, a quadrature acoustic touch sensing operation can utilize twoseparate measurements (e.g., in-phase and quadrature) to eliminatespatial nulls in the touch sensing measurements. In FIG. 29A, for eachtransducer XDUCER1-XDUCER4 during the touch capture phase, sixteenmeasurement time slices 2912 are shown. These sixteen total time slicesshown can correspond to an averaging of eight measurements for in-phasemeasurement and eight measurements for quadrature measurement. Thus,while FIG. 29A illustrates sixteen measurement time slices 2912 fortouch capture and eight measurement time slices force capture, it shouldbe understood that eight sample averages are being illustrated for boththe touch capture and force capture. However, it should be understoodthat the number of averages can be different from eight (e.g., as longas there are two or more measurements to average) without departing formthe scope of the disclosure. Moreover, the number of averages usedduring touch capture phase 2902 can be different from the number ofaverages used during the force capture phase 2904. Furthermore, thesequence of the detection from multiple transducers can be arranged in adifferent order from the one illustrated without departing from thescope of the present disclosure. In addition, the sequence of detectionof the multiple transducers can be changed in different frames withoutdeparting from the scope of the present disclosure. In yet otherexamples, a subset of the transducers can be sampled in each framerather than sampling all of the transducers in every frame withoutdeparting from the scope of the present disclosure. In some examples,the measurement time slices 2912 during the touch capture phase 2902 canhave a longer duration than measurement time slices 2912 during theforce capture phase 2904 as illustrated in FIG. 29B. In some examples,the difference in durations of the touch capture phase 2902 and theforce capture phase 2904 can relate to the difference in distance thatan acoustic wave travels in the touch phase (e.g., across the coverglass 601 or 611 above) as compared to the distance that an acousticwave travels in the force phase 2904 (e.g., through the thickness ofdeformable material 604 or 614 above). To illustrate this point, FIG.29B illustrates an exemplary timing diagram where the respective receivedurations (Rx1-RxN) for the force phase 2904 measurements are shorterthan the respective receive duration (Rx1-RxN) for the touch phase 2902measurements as described immediately above. As a result, FIG. 29Billustrates that the total duration for the force phase 2904 can beshorter than the total duration of the touch phase 2902 even when thesame total numbers of transmit and receives are performed during eachphase (e.g., when half as many averages are taken for touch capture 2902and force capture 2904 in the case of quadrature touch measurements). Itshould be understood that the duration of various phases illustrated inthe timing diagrams of FIGS. 29A-29B, e.g., touch capture 2902, forcecapture 2904, data transfer 2906, algorithm 2908, idle 2910, etc. arenot necessarily drawn to scale and are provided for the purposes ofillustration.

In some examples, force detections for each of the transducersXDUCER1-XDUCER4 can be performed simultaneously to reduce the totalduration of force measurements during the force phase 2904. In such anexample, each transducer XDUCER1-XDUCER4 can be provided with a transmitcircuit to drive the transducer and an analog front end to receive theforce measurement signals (e.g., from reflections in the deformablematerial 604 or 614 above coupled to each individual transducer e.g.,502A-502D above). In some examples, a single transmit circuit can beused to sequentially drive each individual transducer XDUCER1-XDUCER4with a slight time delay between driving each transducer, and thensimultaneously capture the force measurement signals at four analogfront ends from each of the transducers XDUCER1-XDUCER4 to reduce thetime for force detection.

FIGS. 30A and 30B illustrate timing diagrams for a quadrature acoustictouch and force sensing mode of operation. Specifically, in the mode ofoperation illustrated in FIGS. 30A and 30B, the touch and force capturephases are combined into a touch and force capture phase 3020. This canbe accomplished by performing a force receiving function 3022 and atouch receive function 3024 as illustrated in FIG. 30B during a singlecombined Rx function 3016 (e.g., as described above with reference toFIG. 20B). In some examples, the force and touch receive functions canbe performed after a single transmit (Tx) function 3014 because forcereflections arrive at the transducer and any ringing associated with theforce measurement can settle before touch reflections associated withtouch measurement are received at the transducer (e.g., as describedwith reference to FIG. 7 above). In some examples, the timingillustrated in FIGS. 30A and 30B can most preferably be used whensignals for the force sensing occur during a dead zone for touch signalsfrom touch sensing. In other words, depending on the geometries andmaterial properties of the deformable material (e.g., 604 or 614 above)and cover glass (e.g., 601 and 611 above), the signals for touch captureand force capture can be temporally isolated in two distinct timewindows (e.g., force receive 3022 and touch receive 3024) following asingle Tx function 3014.

Similar to the description of FIGS. 19A-20B and 28A-29B above, FIG. 30Ashows that the combined touch and force capture phase 3020 can includemultiple measurement time slices 3012 that can be used to obtainmultiple measurements for averaging. For example, each measurementtiming slice 3012 can include a transmit (Tx) function 2914 (e.g.,driving a signal onto the transducer to produce an acoustic wave) and areceive (Rx) function 2916 (e.g., receiving reflected signalscorresponding to both touch and force measurements). The sixteen totalmeasurement time slices 3012 shown in FIG. 30A can correspond to anaveraging of eight measurements for in-phase measurement, eightmeasurements for quadrature measurement, and sixteen measurements forthe force measurement (which can be taken regardless of whether thetouch measurement is associated with in-phase or quadrature). As shouldbe understood from the disclosure above, respective force measurements3024 can be averaged together and respective touch measurements 3022(grouped by in-phase and quadrature measurements) can also be averagedtogether. In some examples, the duration of force receive function 3022can be shorter than touch receive function 3024. Although FIG. 30described averaging of eight measurements for touch and sixteenmeasurements for force, it should be understood that averaging can usedwith a different number of measurements than eight, (e.g., as long asthere are two or more measurements to average) without departing fromthe scope of the disclosure. Furthermore, the sequence of the detectionfrom multiple transducers can be arranged in a different order from theone illustrated without departing from the scope of the presentdisclosure. In addition, the sequence of detection of the multipletransducers can be changed in different frames without departing fromthe scope of the present disclosure. In yet other examples, a subset ofthe transducers can be sampled in each frame rather than sampling all ofthe transducers in every frame without departing from the scope of thepresent disclosure. It should be understood that the duration of variousphases illustrated in the timing diagrams of FIGS. 30A-30B, e.g., touchand force capture 3020, data transfer 3006, algorithm 3008, idle 3010,etc. are not necessarily drawn to scale and are provided for thepurposes of illustration. In some examples, the data transfer period3006, the algorithm period 3008, or both, can be pipelined orinterleaved with the detection without departing from the scope of thepresent disclosure.

FIGS. 31A-31C illustrate exemplary switching configurations forquadrature acoustic touch and force sensing systems according toexamples of the disclosure. Transducer 3102 illustrated in FIG. 31A caninclude a four spatial differential electrode configuration withelectrodes 3104A-3104D disposed on a first side of the transducer andcommon electrode 3106 disposed on a second side of the transducer. Itshould be recognizable that the four spatial differential electrodeconfiguration illustrated in FIG. 31 can correspond to the configurationdescribed above with reference to FIG. 11B. The outputs/inputs ofelectrodes 3104A, 3104B, 3104C, 3104D, and 3106 can be connected totouch and force control and readout circuitry 3108A or 3108B of eitherFIG. 31A or 31B, respectively, for acoustic touch and force sensing.

Touch and force control and readout circuitry 3108A of FIG. 31A caninclude four analog front end (AFE) amplifiers 3112, 3116, 3120, and3124, the output of which can be connected to sense circuitry 3110. Theoutput of sense circuitry 3110 can be connected to the inputs oftransmitter 3128. In some examples, electrode 3104A can be connected toa first input terminal of AFE amplifier 3112 via switch 31S1, the outputof electrode 3104B can be connected to a first input terminal of AFEamplifier 3116 via switch 31S2, the output of electrode 3104C can beconnected to a first input terminal of AFE amplifier 3120 via switch31S3, and the output of electrode 3104D can be connected to a firstinput terminal of AFE amplifier 3124 via switch 31S4 (as indicated byconnection labels 31A-31D, respectively). The second terminal of AFEamplifiers 3112, 3116, 3120, and 3124 can each connected to ground orany desired reference voltage source. In addition, electrodes 3104A,3104B, 3104C, and 3104D can be connected to a first output terminal oftransmitter 3128 via switches 31S5, 31S6, 31S7, and 31S8, respectively(as indicated by connection labels 31A-31D). Electrode 3106 can beconnected to a second output terminal of transmitter 3106 via switch31S9 (as indicated by connection 31E). During a combined touch and forcereceive (Rx) function, switches 31S1, 31S2, 31S3, and 31S4 can beclosed, and switches 31S5, 31S6, 31S7, 31S8, and 31S9 can be open. Theswitch configuration during the combined touch and force Rx function canallow each AFE 3112, 3116, 3120, and 3124 to receive a signal fromelectrodes 3104A, 3104B, 3104C, and 3104D, respectively. During atransmit (Tx) function switches 31S5, 31S6, 31S7, 31S8, and 31S9 can beclosed, and switches 31S1, 31S2, 31S3, and 31S4 can be open. The switchconfiguration during the Tx function can allow transmitter 3128 to drivethe electrodes 3104A, 3104B, 3104C, 3104D, and 3106 of transducer 2202to create an electric potential across transducer 3102 and generate anacoustic wave. Notably, exemplary switching configuration 3100A iscompatible with the mode of operation illustrated in FIGS. 28A-28B(e.g., the configuration that allows signals for in-phase touch,quadrature touch, and force to be sensed simultaneously). In someexamples, sense circuitry 3110 can include one or more ofdigital-to-analog converters (DAC) 402A, filter 402B, gain and offsetcorrection circuit 412, demodulation circuit 414, filter 416,analog-to-digital converter (ADC) 418, input/output (I/O) circuit 420,acoustic scan control circuit 422, force detection circuit 424,processor SoC 430, host processor 432, auxiliary processor 434, and/orany other sense circuitry described above with reference to FIG. 4. Insome examples, sense circuitry 3110 can be on a different chip from AFE3112, AFE 3116, AFE 3120, AFE 3124, transmitter 3128, switches31S1-31S9, and sources 3114, 3118, 3122, and 3126. In some examples,inputs of AFE amplifiers 3112, 3116, 3120, and 3124 can be connected toa first transducer for receiving, and the outputs of transmitter 3128can be connected to a second transducer, different than the firsttransducer, for transmitting. In some examples, the transmit and receivecircuitry 3110 can be included on a silicon chip. In some examples, thetransmit circuitry can be designed to drive higher voltages (orcurrents) to produce sufficient motion in the transducer to generate anacoustic wave in the surface of a device, and the receive circuitry canbe designed for receiving smaller amplitude reflected energy.Accordingly, in some examples, the transmit circuitry and receivecircuitry can be included on different silicon chips to avoidinterference with the operation of the receive circuitry by the transmitcircuitry. In some examples, common electrode 3106 can be floatingduring the receive (Rx) function to cancel out common mode signals(e.g., as described above with reference to electrode 1407 of FIGS. 14Band 14C).

Touch and force control and readout circuitry 3108B of FIG. 31B isconfigured similarly to touch and force control and readout circuitry3108A of FIG. 31A with the exception of analog signal combination blocks3126, 3128, and 3130. Each of these blocks can include circuitry (e.g.,an inverting summer) for combining the signals measured by the AFEs3112, 3116, 3120, and 3124 to generate in-phase touch, quadrature touch,and force measurements. The formula for the electrode combinations isillustrated above each respective block 3126 (e.g., AB-CD), 3128 (e.g.,AD-BC), and 3130 (e.g., AC-BD). As illustrated, the outputs of AFEamplifiers 3112 and 3116 can be combined to produce signal AB, theoutputs of amplifiers 3112 and 3120 can be combined to produce signalAC, and so-on, to create all of the signal combinations AB, AC, AD, BC,BD, and CD that are used by the analog signal combination blocks 3126,3128, and 3130 to generate the in-phase touch, quadrature touch, andforce measurements simultaneously. The outputs of the AFE amplifiers3112, 3116, 3120, and 3124 are shown with respective connections to thecombination blocks to provide the electrode combinations for forming anin-phase touch (Touch I), quadrature touch (Touch Q) and force signal inparallel. In the figure, connections between intersecting lines areindicated by large black dots at the crossing point and lines crossingwithout large black dots have no connection. It should be understoodthat the AFE outputs are shown directly driving each of the combinationblocks 3126, 3128, and 3130 buffers (not shown) can be placed betweenthe AFEs and each of the combination block inputs. Touch I circuitry3130 can be configured to determine the difference between force signalsAB and CD, and feed that difference to sense circuitry 3110. Similarly,the outputs of AFE amplifiers 3112 and 3124 can be combined (e.g., AD)and connected to a first input of touch Q circuitry 3132, and theoutputs of AFE amplifiers 3116 and 3120 can be combined (e.g., BC) andconnected to a second input of touch Q circuitry 3132. Touch Q circuitry3132 can be configured to determine the difference between touch signalsAD and BC, and feed that difference to sense circuitry 3110. In someexamples, the functions performed at touch circuitry 3110 and 3112 canbe performed simultaneously. The remaining elements of touch and forcecontrol and readout circuitry 3108B can operate as described withreference to touch and force control and readout circuitry 3108A of FIG.31A above.

FIG. 31C illustrates an exemplary circuit configuration for combinationblocks 3126, 3128, and 3130 in FIG. 31B above. In particular, the inputvoltages V_(A), V_(B), V_(C), and V_(D) as shown in FIG. 31C cancorrespond to the outputs of AFEs 3112, 3116, 3120, and 3124,respectively, and are arranged to match the input order shown connectedto combination block 3126 in 31B above. As shown in FIG. 31C, resistorsall having a value R can be arranged with the operational amplifier 3150such that the output voltage Vout is equal to(V_(A)+V_(B))−(V_(C)+V_(D)). This result corresponds to the output(e.g., AB-CD) for combination block 3126 that can be used for in-phasetouch as described above in FIG. 31B. It should be understood that thesame configuration can be used to form the signals output signals AD-BCfor quadrature touch and AC-BD for force touch at combination blocks3128 and 3130. As shown in FIG. 31C, the output of the combinationblocks can be single ended, although a differential output is shown forblocks 3126, 3128, and 3130 above. Furthermore, the exact configurationshown in FIG. 31C can be replaced with alternative circuitconfigurations that can add and subtract the voltage signals V_(A),V_(B), V_(C), and V_(D) to produce the in-phase touch, quadrature touch,and force signals without departing from the scope of the presentdisclosure. The configuration shown in FIG. 31C is not limiting and isprovided only to provide one example of a combination circuit that canbe used to produce the desired signals for the purpose of illustration.

FIG. 32 illustrates exemplary switching configuration 3200 forquadrature acoustic touch and force sensing systems according toexamples of the disclosure. Transducer 3202 can include a four spatialdifferential electrode configuration with electrodes 3204A-3204Ddisposed on a first side of the transducer and electrode 3206 disposedon a second side of the transducer. It should be recognizable that thefour spatial differential electrode configuration illustrated in FIG. 32can correspond to the configuration described above with reference toFIG. 11B. Electrodes 3204A, 3204B, 3204C, 3204D, and 3206 can beconnected to touch and force control and readout circuitry 3208 foracoustic touch and force sensing. Touch and force control and readoutcircuitry 3208 can include analog front end (AFE) amplifier 3212, theoutput of which can be connected to sense circuitry 3210. The output ofsense circuitry 3210 can be connected to the inputs of transmitter 3214.In some examples, electrodes 3204A, 3204B, 3204C, and 3204D can beconnected to a first input terminal of AFE amplifier 3212 via switches32S1, 32S2, 32S3, and 32S4, respectively (as indicated by connectionlabels 32A-32D). Electrodes 3204A, 3204B, 3204C, and 3204D can also beconnected to a second input terminal of AFE amplifier 3212 via switches32S5, 32S6, 32S7, and 32S8, respectively (also as indicated byconnection labels 32A-32D). Similarly, electrodes 3204A, 3204B, 3204C,and 3204D can be connected to a first output terminal of transmitter3214 via switches 32S9, 32S10, 32S11, and 32S12, respectively (also asindicated by connection labels 32A-32D). Electrode 3206 can be connectedto a second output terminal of transmitter 3214 via switch 32S13 (asindicated by connection label 32E). During an in-phase touch receive(Rx) function (Touch-I), switches 32S1, 32S2, 32S7, and 32S8 can beclosed, and switches 32S3, 32S4, 32S5, 32S6, 32S9, 32S10, 32S11, 32S12,and 32S13 can be open. The switch configuration during the in-phasetouch Rx function can allow the AFE 3212 to receive combined electricalsignals from the electrodes 3204A and 3204B at a first terminal of AFE3212 and to receive combined electrical signals from electrodes 3204Cand 3204D at a second terminal of AFE 3212. This can allow sensecircuitry 3210 to detect the in-phase touch signal from the electrodescorresponding to a differential measurement of 32A, 32B vs. 32C, 32D(e.g., as shown in FIG. 18A above). During a quadrature touch Rx(Touch-Q) function, switches 32S1, 32S4, 32S6, and 32S7 can be closed,and switches 32S2, 32S3, 32S5, 32S8, 32S9, 32S10, 32S11, 32S12, and32S13 can be open. The switch configuration during the quadrature touchRx function can allow the AFE 3212 to receive combined electricalsignals from the electrodes 3204A and 3204D at a first input of AFE 3212and to receive combined electrical signals from electrodes 3204B and3204C at a second terminal of AFE 3212. This can allow sense circuitry3210 to detect the quadrature touch signal from the electrodescorresponding to a differential measurement of 32A, 32D vs. 32B, 32C(e.g., as shown in FIG. 18B above). During a force receive (Rx)function, switches 32S1, 32S3, 32S6, and 32S8 can be closed, andswitches 32S2, 32S4, 32S5, 32S7, 32S9, 32S10, 32S11, 32S12, and 32S13can be open. The switch configuration during the force Rx function canallow the AFE 3212 to receive electrical signals from the electrodes3204A and 3204C at a first terminal of AFE 3212 and to receiveelectrical signals from electrodes 3204B and 3204D at a second terminalof AFE 3212. This can allow sense circuitry 3210 to detect the forcesignal from the electrodes corresponding to a differential measurementof 32A, 32C vs. 32B, 32D (e.g., as illustrated in FIG. 18C above). Inthe arrangement shown in FIG. 32, the force Rx function can beassociated with a spatial frequency that is twice the spatial frequencyof the in-phase touch and quadrature touch Rx functions. During each ofthe Rx functions, the electrode 3206 can be left floating for performingcommon mode rejection as described above with regarding to FIGS.14A-14C. During a transmit (Tx) function switches 32S9, 32S10, 32S11,32S12, and 32S13 can be closed, and switches 32S1-31S8 can be open. Theswitch configuration during the Tx function can allow transmitter 3214to drive the electrodes 3204A, 3204B, 3204C, 3204D, and 3206 oftransducer 3202 to create an electric potential across transducer 3206and generate an acoustic wave. Notably, exemplary switchingconfiguration 3200 is compatible with the modes of operation illustratedin FIGS. 29A-30B. In some examples, additional AFE amplifiers can beincorporated to reduce the total time for reading all of the touch andforce electrode groupings. For example, a second AFE amplifier can beincorporated such that a first AFE amplifier can be dedicated for touchdetection, and the second AFE amplifier can be dedicated for forcedetection. In some examples, sense circuitry 3210 can include one ormore of digital-to-analog converters (DAC) 402A, filter 402B, gain andoffset correction circuit 412, demodulation circuit 414, filter 416,analog-to-digital converter (ADC) 418, input/output (I/O) circuit 420,acoustic scan control circuit 422, force detection circuit 424,processor SoC 430, host processor 432, auxiliary processor 434, and/orany other sense circuitry described above with reference to FIG. 4. Insome examples, sense circuitry 3210 can be on a different chip from AFE3212, transmitter 3214, and switches 32S1-32S13. In some examples, AFEamplifier 3212 can be connected to a first transducer for receiving, andthe outputs of transmitter 3214 can be connected to a second transducer,different than the first transducer, for transmitting. In some examples,the touch and force control and readout circuitry 3208 can be includedon a silicon chip. In some examples, the transmit circuitry can bedesigned to drive higher voltages (or currents) to produce sufficientmotion in the transducer to generate an acoustic wave in the surface ofa device, and the receive circuitry can be designed for receivingsmaller amplitude reflected energy. Accordingly, in some examples, thetransmit circuitry and receive circuitry can be included on differentsilicon chips to avoid interference with the operation of the receivecircuitry by the transmit circuitry.

FIG. 33 illustrates exemplary switching configuration 3300 forquadrature acoustic touch and force sensing systems according toexamples of the disclosure. Transducer 3302 can include a four spatialdifferential electrode configuration with electrodes 3304A-3304Ddisposed on a first side of the transducer and electrodes 3306E and3306F disposed on a second side of the transducer. It should berecognizable that the spatial differential electrode configurationillustrated in FIG. 33 can correspond to the configuration describedabove with reference to FIG. 11B above. Electrodes 3304A, 3304B, 3304C,3304D, 3306E, and 3306F can be connected to touch and force control andreadout circuitry 3308 for acoustic touch and force sensing. Touch andforce control and readout circuitry 3308 can include analog front end(AFE) amplifier 3312, the output of which can be connected to sensecircuitry 3310. Outputs from sense circuitry 3310 can be connected tothe inputs of transmitter 3314. In some examples, electrodes 3304A,3304B, 3304D, and 3304E can be connected to a first input terminal ofAFE amplifier 3312 via switches 33S1, 33S2, 33S3, and 33S4, respectively(as indicated by connection labels 33A-33D). Electrodes 3304B, 3304C,3304D, and 3304F can also be connected to a second input terminal of AFEamplifier 3312 via switches 33S5, 33S6, 33S7, and 33S8, respectively (asindicated by connection labels 33B, 33C, 33D, and 33F). In addition,electrodes 3304A, 3304B, 3304C, and 3304D can be connected to a firstoutput terminal of transmitter 3314 via switches 33S9, 33S10, 33S11, and33S12, respectively (as indicated by connection labels 33A-33D).Electrodes 3306E and 3306F can be connected to a second output terminalof transmitter 3314 via switches 33S13 and 33S14, respectively (asindicated by connection labels 33E-33F). During an in-phase touchreceive (Rx) function (Touch-I), switches 33S1, 33S2, 33S6, and 33S7 canbe closed, and switches 33S3, 33S4, 33S5, 33S8, 33S9, 33S10, 33S11,33S12, 33S13, and 33S13 can be open. The switch configuration during thetouch I Rx function can allow the AFE 3312 to receive electrical signalsfrom the electrodes 3304A and 3304B at a first terminal of AFE 3312 andto receive electrical signals from electrodes 3304C and 3304D at asecond terminal of AFE 3312. This can allow sense circuitry 3310 todetect the in-phase touch signal from the electrodes corresponding to adifferential measurement of 33A, 33B vs. 33C, 33D. During a quadraturetouch receive (Rx) function (Touch-Q), switches 33S1, 33S3, 33S5, and33S6 can be closed, and switches 33S2, 33S4, 33S7, 33S8, 33S9, 33S10,33S11, 33S12, 33S13, and 33S14 can be open. The switch configurationduring the quadrature touch Rx function can allow the AFE 3312 toreceive electrical signals from the electrodes 3304A and 3304D at afirst terminal of AFE 3312 and to receive electrical signals fromelectrodes 3304B and 3304C at a second terminal of AFE 3312. This canallow sense circuitry 3310 to detect the quadrature touch signal fromthe electrodes corresponding to a differential measurement of 33A, 33Dvs 33B, 33C. During a force receive (Rx) function, switches 33S4 and33S8 can be closed, and switches 33S1, 33S2, 33S3, 33S5, 33A6, 33S7,33S9, 33S10, 33S11, 33S12, 33S13, and 33S14 can be open. The switchconfiguration during the force Rx function can allow the AFE 3312 toreceive electrical signals from the electrodes 3304E and 3304F. This canallow sense circuitry 3310 to detect the force signal from theelectrodes corresponding to a differential measurement of E vs. F.During each of the Rx functions, the electrode opposite side electrodes(e.g., E and F while A, B, C, D are being sensed, or A, B, C, and Dwhile E and F are being sensed) can be left floating for performingcommon mode rejection as described above with regard to FIGS. 14A-14Cabove. It should be understood from the disclosure above that the pitchof the 3306E and 3306F can correspond to a lower spatial frequency(e.g., half of the spatial frequency) for force touch measurementscompared to in-phase touch and quadrature touch measurements. During atransmit (Tx) function switches 33S9-33S14 can be closed, and switches33S1-33S8 can be open. The switch configuration during the Tx functioncan allow transmitter 3314 to drive the electrodes 3304A, 3304B, 3304C,3304D, 3306E, and 3306F of transducer 3302 to produce an electricpotential across the transducer 3302 and generate an acoustic wave.Notably, exemplary switching configuration 3300 is compatible with themodes of operation illustrated in FIGS. 29A-30B. In some examples,additional AFE amplifiers can be incorporated to make this configurationcompatible with the mode of operation illustrated in FIGS. 28A and 28B(e.g., as described with reference to FIGS. 31A and 31B). In someexamples, a second AFE amplifier can be incorporated such that a firstAFE amplifier can be dedicated for touch detection, and the second AFEamplifier can be dedicated for force detection. In some examples, sensecircuitry 3310 can include one or more of digital-to-analog converters(DAC) 402A, filter 402B, gain and offset correction circuit 412,demodulation circuit 414, filter 416, analog-to-digital converter (ADC)418, input/output (I/O) circuit 420, acoustic scan control circuit 422,force detection circuit 424, processor SoC 430, host processor 432,auxiliary processor 434, and/or any other sense circuitry describedabove with reference to FIG. 4. In some examples, sense circuitry 3310can be on a different chip from AFE 3312, transmitter 3314, and switches33S1-33S14. In some examples, inputs of AFE amplifier 3312 can beconnected to a first transducer for receiving, and the outputs oftransmitter 3314 can be connected to a second transducer, different thanthe first transducer, for transmitting. In some examples, the touch andforce control and readout circuitry 3308 can be included on a siliconchip. In some examples, the transmit circuitry can be designed to bedriven by higher voltages (or currents) to produce sufficient motion inthe transducer to generate an acoustic wave in the surface of a device,and the receive circuitry can be designed for receiving smalleramplitude reflected energy. Accordingly, in some examples, the transmitcircuitry and receive circuitry can be included on different siliconchips to avoid interference with the operation of the receive circuitryby the transmit circuitry.

FIG. 34 illustrates exemplary switching configuration 3400 forquadrature acoustic touch and force sensing systems according toexamples of the disclosure. Transducer 3402 can include a eight spatialdifferential electrode configuration with electrodes 3404A, 3404B,3404C, 3404D, 3404A1, 3404B1, 3404C1, and 3404D1 disposed on a firstside of the transducer and electrode 3406 on a second side of thetransducer. Electrodes 3404A, 3404B, 3404C, 3404D, 3404A1, 3404B1,3404C1, 3404D1, and 3406 can be connected to touch and force control andreadout circuitry 3408 for acoustic touch and force sensing. Touch andforce control and readout circuitry 3408 can include analog front end(AFE) amplifier 3412, the output of which can be connected to sensecircuitry 3410. Outputs from sense circuitry 3410 can be connected tothe inputs of transmitter 3414. In some examples, electrodes 3404A,3404B, 3404A1, 3404B1, 3404C, 3404C1, and 3404D can be connected to afirst input terminal of AFE amplifier 3412 via switches 34S1, 34S2,34S3, 34S4, 34S5, 34S6, and 34S7, respectively (as indicated byconnection labels 34A, 34B, 34A1, 34B1, 34C, 34C1, and 34D). Electrodes3404C, 3404D, 3404C1, 3404D1, 3404A, 3404A1, and 3404B1 can also beconnected to a second input terminal of AFE amplifier 3412 via switches34S8, 34S9, 34S10, 34S11, 34S12, 34S13, and 34S14, respectively (asindicated by connection labels 34C, 34D, 34C1, 34D1, 34A, 34A1, and34B1). Similarly, electrodes 3404A, 3404B, 3404C, 3404D, 3404A1, 3404B1,3404C1, and 3404D1 can be connected to a first output terminal oftransmitter 3314 via switches 34S15, 34S16, 34S17, 34S18, 34S19, 34S20,34S21, and 34S22, respectively (as indicated by connection labels 34A,34B, 34C, 34D, 34A1, 34B1, 34C1, and 34D1). Electrode 3406 can beconnected to a second output terminal of transmitter 3314 via switch33S23 (as indicated by connection label 34E). It should be understoodthat, while not illustrated, electrodes 3404A, 3404B, 3404C, 3404D,3404A1, 3404B1, 3404C1, and 3404D1 can represent electrodeconfigurations as described above with reference to FIGS. 17A-17C.During an in-phase touch receive (Rx) function (Touch-I), switches 34S1,34S2, 34S3, 34S4, 34S8, 34S9, 34S10, and 34S11 can be closed, andswitches 34S5-34S7, and 34S12-34S23 can be open. The switchconfiguration during the in-phase touch Rx function can allow the AFE3412 to receive electrical signals from the electrodes 3404A, 3404B,3404A1, and 3404B1 at a first terminal of AFE 3312 and to receiveelectrical signals from electrodes 3404C, 3404D, 3404C1, and 3404D1 at asecond terminal of AFE 3412. This can allow sense circuitry 3410 todetect the in-phase touch signal from the electrodes corresponding to adifferential measurement of ABA1B1 and CDC1D1. During a quadrature touchreceive (Rx) function (Touch-Q), switches 34S2, 34S4, 34S5, 34S6, 34S9,34S11, 34S12, and 34S13 can be closed, and switches 34S1, 34S3, 34S7,34S8, and 34S14-34S23 can be open. The switch configuration during thequadrature touch Rx function can allow the AFE 3412 to receiveelectrical signals from the electrodes 3404B, 3404B1, 3404C, and 3404C1at a first terminal of AFE 3412 and to receive electrical signals fromelectrodes 3404A, 3404A1, 3404D, and 3404D1 at a second terminal of AFE3412. This can allow sense circuitry 3410 to detect the quadrature touchsignal from the electrodes corresponding to a differential measurementof BCB1C1 vs ADA1D1. During a force receive (Rx) function, switches34S1, 34S2, 34S5, 34S7, 34S10, 34S11, 34S13, and 34S14 can be closed,and switches 34S3, 34S4, 34S6, 34S8, 34S9, 34S12 and 34S15-34S23 can beopen. The switch configuration during the force Rx function can allowthe AFE 3412 to receive electrical signals from the electrodes 3404A,3404B, 3404C, and 3404D at a first terminal of AFE 3412 and to receiveelectrical signals from electrodes 3404A1, 3404B1, 3404C1, and 3404D1 ata second terminal of AFE 3412. This can allow sense circuitry 3410 todetect the force signal from the electrodes corresponding to adifferential measurement of ABCD and A1B1C1D1. During each of the Rxfunctions, the electrode 3406 can be left floating for performing commonmode rejection as described above with regarding to FIGS. 14A-14C.During a transmit (Tx) function switches 34S15-34S23 can be closed, andswitches 34S1-34S14 can be open. The switch configuration during the Txfunction can allow transmitter 3414 to drive the electrodes 3404A,3404B, 3404C, 3404D, 3404A1, 3404B1, 3404C1, 3404D1, and 3306E oftransducer 3302 to generate an acoustic wave. Notably, exemplaryswitching configuration 3400 is compatible with the modes of operationillustrated in FIGS. 29A-30B. Similar to the example illustrated in FIG.33 above, the switching scheme illustrated in FIG. 34 can measure forceat a spatial frequency that is half the spatial frequency of thein-phase touch and quadrature touch measurements. However, unlike FIG.33 above, differential measurement electrodes 3404A-3404D1 all can bedisposed on one side of the transducer 3406. This configuration cansimplify forming electrical connections to all of the transducerelectrodes (e.g., 3404A-3404D1 and 3406) from one side of transducer.Since electrodes 3404A-3404D1 are already on one side of the transducer3402, only electrode 3406 would need to be routed to the opposite sideto achieve the goal of single-sided connections described immediatelyabove. On the other hand, in FIG. 33 above, both electrodes 3306E and3306F would need to be routed to the opposite side of transducer 3302 toachieve the same result. This benefit comes with a trade-off of moretotal electrodes on the transducer (nine in FIG. 34 compared to six inFIG. 33) and correspondingly more switches for connecting to increasednumber of electrodes. In some examples, additional AFE amplifiers (e.g.,eight in total) can be incorporated to make this configurationcompatible with the mode of operation illustrated in FIGS. 28A and 28B(e.g., as described with reference to FIGS. 31A and 31B). In someexamples, a second AFE amplifier can be incorporated such that a firstAFE amplifier can be dedicated for touch detection, and the second AFEamplifier can be dedicated for force detection. In some examples, sensecircuitry 3410 can include one or more of digital-to-analog converters(DAC) 402A, filter 402B, gain and offset correction circuit 412,demodulation circuit 414, filter 416, analog-to-digital converter (ADC)418, input/output (I/O) circuit 420, acoustic scan control circuit 422,force detection circuit 424, processor SoC 430, host processor 432,auxiliary processor 434, and/or any other sense circuitry describedabove with reference to FIG. 4. In some examples, sense circuitry 3410can be on a different chip from AFE 3412, transmitter 3414, and switches24S1-34S23. In some examples, inputs of AFE amplifier 3412 can beconnected to a first transducer for receiving, and the outputs oftransmitter 3414 can be connected to a second transducer, different thanthe first transducer, for transmitting. In some examples, the touch andforce control and readout circuitry 3408 can be included on a siliconchip. In some examples, the transmit circuitry can be designed to drivehigher voltages (or currents) to produce sufficient motion in thetransducer to generate an acoustic wave in the surface of a device, andthe receive circuitry can be designed for receiving smaller amplitudereflected energy. Accordingly, in some examples, the transmit circuitryand receive circuitry can be included on different silicon chips toavoid interference with the operation of the receive circuitry by thetransmit circuitry.

FIGS. 35A-35B illustrate an exemplary transmitter configuration foracoustic touch and force sensing systems according to examples of thedisclosure. The exemplary transmitter can represent any of the variousTx blocks described in FIGS. 21-27 and 31-34 above. It should beunderstood that the exemplary Tx block is provided only for the purposesof illustration, and that any circuit configuration capable of driving apiezoelectric transducer to produce acoustic waves can be used withoutdeparting from the scope of the present disclosure. Specifically, FIG.35A illustrates transmitter 3514 with inputs 3520A and 3520B and outputs3522A and 3522B. FIG. 35B illustrates a detailed configuration oftransmitter 3514 of FIG. 35A illustrating a boost converterconfiguration for providing the Tx drive signal. In the illustration,the boost circuit 3524 can boost the input voltage to a suitable drivevoltage for the transistor. In the illustrated voltage boostconfiguration of FIG. 35B, a single ended output can be formed as thenegative output terminal is connected to ground 3528. Accordingly, adifferential drive for the transducer can be provided using switches toinvert the polarity of the drive signals as will be shown in FIG. 36Bbelow.

FIGS. 36A-36B illustrate exemplary transmitter configurations foracoustic touch and force sensing systems according to examples of thedisclosure. Specifically, FIG. 36A repeats the Tx 3614 Tx configurationshown in FIGS. 31A-31B and FIG. 32 for a transducer with four electrodes36A-36D on one side and one electrode 36E on the opposite side. Asdescribed in FIGS. 31A-31B and FIG. 32, during the transmit phase forthe configuration in 36A, all of the switches 36S5-36S9 can be closed,and a differential signal can be driven by the differential Tx 3614across the two sides of a transducer such as 3102 or 3202 above. Asdescribed, the switch configuration shown in FIG. 36A can be used with afully differential transmit circuit 3614, but is provided here primarilyas a reference point for the switch configuration shown in FIG. 36B thatcan be used to provide differential drive to the transducer using asingle ended boost converter as described in FIG. 36A above.

FIG. 36B illustrates a switching configuration for providing adifferential drive signal based on a single-ended output Txconfiguration such as the exemplary Tx configuration 3514 described inFIG. 36A. The boost converter 3614B can be identical to the boostconverter described above in FIG. 35B. Switches 36S5, 36S6, 36S7, 36S8,and 36S9 can correspond directly to the switches having the same numbersas shown in FIG. 36A above. Thus, when those switches are closed, thepositive output of the boost converter 3614B can be connected toelectrodes on one side of the transducer, while ground 3624 can beconnected to the opposite side of the transducer. Switches 36S10, 36S11,36S12, 36S13, and 36S14 can provide analogous connections to theswitches 36S5-36S9, but with the opposite polarity. By switching backand forth between these closing switches 36S5-36S9 (while opening theothers) and closing switches 36S10-36S14 (while opening the others), adifferential drive can be applied to a transducer based on a singleended voltage boost configuration as illustrated in FIGS. 35B and 36B.More generally, the switching principle illustrated in FIG. 36B can beapplied to create a differential drive for a transducer from any singleended source having a sufficient output voltage to drive the transducerto produce acoustic waves as described throughout the disclosure.

FIGS. 37A-37Q illustrate exemplary pixelated transducers 3700A-Qaccording to examples of the disclosure. As described herein, apixelated transducer replaces one or both conventional electrodes of atransducer (e.g., first electrode 332 and/or second electrode 334 inFIG. 3C) into multiple electrodes. The pixelated transducers 3700A-Mcan, for example, include a piezoelectric material 3701 and a pluralityof separated electrodes. In some examples (e.g., illustrated in FIGS.37H-37N), an electrode layer on one side of piezoelectric material 3701can be pixelated (including a plurality of separated electrodes). Insome examples (e.g., illustrated in FIGS. 37A-37G), a first electrodelayer on a first side of piezoelectric material 3701 and a secondelectrode layer on a second side of piezoelectric material 3701 can bepixelated. In some examples, the pitch of the upper electrodes can bethe same as the pitch of the lower electrodes. In some examples, thepitch of the upper electrodes can be different than the pitch of thelower electrodes. In some examples, the transducer can further includean insulating material 3703, such as an epoxy or another suitablenon-conductive material (e.g., plastic, ceramic, etc.). Insulatingmaterial 3703 can provide a surface for wraparound or other connectionsof the electrodes of pixelated transducers 3700A-M. Additionally, usingan insulating material 3703 can reduce noise in the piezoelectricmaterial and maximize the active area of the piezoelectric material3701. The various exemplary pixelated transducers 3700A-M are describedbelow.

FIG. 37A illustrates an exemplary pixelated transducer 3700A accordingto examples of the disclosure. Pixelated transducer 3700A includes firstand second pixelated electrode layers (also referred to as upper andlower pixelated layers based on the orientation illustrated in FIG.37A). For example, pixelated transducer 3700A can include a plurality ofupper electrodes 3704 disposed on a first side of the piezoelectricmaterial 3701 (e.g., top side illustrated in FIG. 37A) and a pluralityof lower electrodes 3706 disposed on a second side of piezoelectricmaterial 3701 (e.g., bottom side illustrated in FIG. 37A). In thepixelated arrangement of FIG. 37A, adjacent upper electrodes 3704 can beseparated from one another by gaps 3770A and adjacent lower electrodes3706 can also be separated from one another by gaps 3770A. The lowerelectrodes 3706 can wrap around from the second side of piezoelectricmaterial 3701 to the first side of piezoelectric material 3701, forexample. The lower electrodes 3706 wrapping around the piezoelectricmaterial 3701 can be separated from corresponding upper electrodes bygaps 3770B. Wrapping around the lower electrodes 3706 to the first sideof the transducer 3700A can allow for simplified connections between thetransducer and a touch and/or force sensing circuit (e.g., via flexcircuit, interposer, direct bonding, etc.).

FIG. 37B illustrates another exemplary pixelated transducer 3700Baccording to examples of the disclosure. Pixelated transducer 3700B cancorrespond to pixelated transducer 3700A, except pixelated transducer3700B can include an insulating material 3703, which can be used, forexample, for bringing the electrodes on the second side of thetransducer to the first side of the transducer. The insulating material3703 can also be used for the connection area between the transducer andthe touch and/or force sensing circuit. For example, pixelatedtransducer 3700B can include a plurality of upper electrodes 3708disposed on a first side of the piezoelectric material 3701 and a firstside of insulating material 3703 (e.g., top side illustrated in FIG.37B) and a plurality of lower electrodes 3710 disposed on a second sideof piezoelectric material 3701 and a second side of insulating material3703 (e.g., bottom side illustrated in FIG. 37B). In the pixelatedarrangement of FIG. 37B, adjacent upper electrodes 3708 can be separatedfrom one another by gaps 3770A and adjacent lower electrodes 3710 canalso be separated from one another by gaps 3770A. The lower electrodes3710 can wrap around from the second side of pixelated transducer 3700Bto the first side of the transducer 3700B. Unlike lower electrodes 3706of pixelated transducer 3700A that wrap around piezoelectric material3701, lower electrodes 3710 can wrap around insulating material 3703 andcan terminate on the first side of insulating material 3703. Using aninsulating material for the wraparound and/or connection can result inimproved stimulation and sensing of the transducer. For example, adifferential signal applied or received across piezoelectric material3701 can have different properties when applied to two opposing sides ofpiezoelectric material 3701 than when the differential signal is appliedto or received from three sides of piezoelectric material 3701(including applying signals to/receiving signals from electrodes on thefirst side of piezoelectric material 3701 in FIG. 37A). The lowerelectrodes 3710 wrapping around the pixelated transducer 3700B (e.g.,wrapping around the insulating material 3703) can be separated fromcorresponding upper electrodes 3708 by gaps 3770B. Wrapping around thelower electrodes 3710 from the second side of pixelated transducer 3700Bto the first side of pixelated transducer 3700B can allow for simplifiedconnections between the transducer and a touch and/or force sensingcircuit (e.g., via flex circuit, interposer, direct bonding, etc.). Itshould be understood that pixelated transducers 3700A-B can be similarlyimplemented with upper electrodes wrapping around from a first side ofpiezoelectric material 3701 to a second side of piezoelectric material3701 instead of implemented with lower electrodes wrapping around asillustrated in FIGS. 37A-B.

FIG. 37C illustrates another exemplary pixelated transducer 3700Caccording to examples of the disclosure. Pixelated transducer 3700C cancorrespond to pixelated transducer 3700A implemented with both upperelectrodes and lower electrodes wrapping around to a common, third sideof piezoelectric material 3701 rather than to a first side (or secondside) of piezoelectric material 3701. Connection between pixelatedtransducer 3700C and touch and/or force circuitry can be made on thethird side of piezoelectric material 3701. For example, transducer 3700can include a plurality of upper electrodes 3712 disposed on a firstside of the piezoelectric material 3701 (e.g., top side illustrated inFIG. 37C) and a plurality of lower electrodes 3714 disposed on a secondside of piezoelectric material 3701 (e.g., bottom side illustrated inFIG. 37C). In the pixelated arrangement of FIG. 37C, adjacent upperelectrodes 3712 can be separated from one another by one or more gaps3770A and adjacent lower electrodes 3714 can also be separated from oneanother by gaps 3770A. The upper electrodes 3712 and lower electrodes3714 can wrap around from the first side (top side) and from the secondside (bottom side) of piezoelectric material 3701, respectively, to acommon, third side of piezoelectric material 3701 (e.g., front rightside illustrated in FIG. 37C). A portion of upper electrodes 3712 and aportion of lower electrodes 3714 wrapping around to the third side ofpiezoelectric material 3701 can be separated from each other by gaps3770B. Wrapping around the upper electrodes 3712 and the lowerelectrodes 3714 to the third side of piezoelectric material 3701 canallow for simplified connections between the transducer and a touchand/or force sensing circuit (e.g., via flex circuit, interposer, directbonding, etc.).

FIG. 37D illustrates another exemplary transducer 3700D according toexamples of the disclosure. Pixelated transducer 3700D can correspond topixelated transducer 3700C, except pixelated transducer 3700D caninclude an insulating material 3703 for wraparound and/or connection.For example, pixelated transducer 3700D can include a plurality of upperelectrodes 3716 disposed on a first side of piezoelectric material 3701(e.g., top side illustrated in FIG. 37D) and a plurality of lowerelectrodes 3718 disposed on a second side of piezoelectric material 3701(e.g., bottom side illustrated in FIG. 37D). In the pixelatedarrangement of FIG. 37D, adjacent upper electrodes 3716 can be separatedfrom one another by gaps 3770A and adjacent lower electrodes 3718 canalso be separated from one another by gaps 3770A. Upper electrodes 3716can extend from the first side of piezoelectric material 3701 to thefirst side of the insulating material 3703 and lower electrodes 3718 canextend from the second side of piezoelectric material 3701 to the secondside of the insulating material 3703. The upper electrodes 3716 andlower electrodes 3718 can wrap around from the first side and the secondside of transducer 3700D, respectively, to a common, third side oftransducer 3700D (e.g., front right side illustrated in FIG. 37D).Unlike upper electrodes 3712 and lower electrodes 3714 of transducer3700C, upper electrodes 3716 and lower electrodes 3718 can wrap aroundand/or terminate on the common third side of insulting material 3703,rather than on the piezoelectric material 3701. Using an insulatingmaterial for the wraparound and/or connection can result in improvedstimulation and sensing of the transducer as discussed above withrespect to FIG. 37B. The upper electrodes 3716 and lower electrodes 3718wrapping around the pixelated transducer 3700D (e.g., by way of theinsulating material 3703) can be separated from one another by gaps3770B. Wrapping around the electrodes 3716 and 3718 from the first andsecond sides of pixelated transducer 3700D to the third side of thepixelated transducer 3700D can allow for simplified connections betweenthe transducer and a touch and/or force sensing circuit (e.g., via flexcircuit, interposer, direct bonding, etc.) on the side of pixelatedtransducer 3700D. It should be understood that pixelated transducers3700C-D can be similarly implemented with upper and lower electrodeswrapping to a common, fourth side of the transducer (e.g., opposite thethird side) instead of wrapping around to the common, third side of thetransducer as illustrated in FIGS. 8C-D.

FIG. 37E illustrates another exemplary pixelated transducer 3700Eaccording to examples of the disclosure. Pixelated transducer 3700E cancorrespond to pixelated transducer 3700C implemented with the upperelectrodes and lower electrodes wrapping around to different third andfourth sides of piezoelectric material 3701 rather than to a commonthird (or fourth) side of piezoelectric material 3701. For example,transducer 3700E can include a plurality of upper electrodes 3720disposed on a first side of the piezoelectric material 3701 (e.g., topside illustrated in FIG. 37E) and a plurality of lower electrodes 3722disposed on a second side of piezoelectric material 3701 (e.g., bottomside illustrated in FIG. 37E). In the pixelated arrangement of FIG. 37E,adjacent upper electrodes 3720 can be separated from one another by gaps3770A and adjacent lower electrodes 3722 can also be separated from oneanother by gaps 3770A. The upper electrodes 3720 can wrap around fromthe first side (top side) of piezoelectric material 3701 to a third sideof piezoelectric material 3701 (e.g., front right side illustrated inFIG. 37E) and lower electrodes 3722 can wrap around from the second side(bottom side) of piezoelectric material 3701 to a fourth side ofpiezoelectric material 3701 (e.g. back left side illustrated in FIG.37E), for example. The upper electrodes 3720 and lower electrodes 3722wrapping around the piezoelectric material 3701 can be on mutuallyexclusive sides of the piezoelectric material, and thereby separatedfrom one another. Connections between the transducer and a touch and/orforce sensing circuit (e.g., via flex circuit, interposer, directbonding, etc.) can be made on the sides of piezoelectric material 3701rather than on the top or bottom of piezoelectric material 3701.

FIG. 37F illustrates another exemplary pixelated transducer 3700Faccording to examples of the disclosure. Pixelated transducer 3700F cancorrespond to pixelated transducer 3700E, except pixelated transducer3700F can include insulating material 3703 disposed on two oppositesides of the piezoelectric material 3701. For example, pixelatedtransducer 3700F can include a plurality of upper electrodes 3724disposed on a first side of the piezoelectric material 3701 (e.g., topside illustrated in FIG. 37F) and a plurality of lower electrodes 3726disposed on a second side of the piezoelectric material 3701 (e.g.,bottom side illustrated in FIG. 37F). Pixelated transducer 3700F caninclude an insulating material 3703 disposed on a third side ofpiezoelectric material 3701 and on a fourth side of piezoelectricmaterial 3701, for example. In the pixelated arrangement of FIG. 37F,adjacent upper electrodes 3724 can be separated from one another by gaps3770A and adjacent lower electrodes 3726 can also be separated from oneanother by gaps 3770A. The upper electrodes 3724 can wrap around fromthe first side (top side) of piezoelectric material 3701 to a third side(e.g., front right side illustrated in FIG. 37F) by way of insulatingmaterial 3703 and lower electrodes 3726 can wrap around from the secondside (bottom side) of piezoelectric material 3701 to a fourth side(e.g., back left side illustrated in FIG. 37F) by way of insulatingmaterial 3703. Unlike the electrodes 3720 and 3722 of transducer 3700E,electrodes 3724 and 3726 can each wrap around insulating material 3703and can terminate on insulating material 3703. Using an insulatingmaterial for the wraparound connection can result in improvedstimulation and sensing of the transducer as described above. Wrappingaround the upper electrodes 3724 from the first side to the third sideand wrapping around the lower electrodes 3726 from the second side tothe fourth side can allow for connections between the transducer and atouch and/or force sensing circuit (e.g., via flex circuit, interposer,direct bonding, etc.) via the sides of pixelated transducer 3700F. Itshould be understood that pixelated transducers 3700E-F can be similarlyimplemented with upper electrodes wrapping to a fourth side of thetransducer and lower electrodes wrapping to a third side of thetransducer instead of upper electrodes wrapping to a third side of thetransducer and lower electrodes wrapping to a fourth side of thetransducer as illustrated in FIGS. 8E-F.

FIG. 37G illustrates another exemplary pixelated transducer 3700Gaccording to examples of the disclosure. Pixelated transducer 3700G cancorrespond to pixelated transducer 3700A implemented without awraparound. For example, transducer 3700G can include a plurality ofupper electrodes 3728 disposed on a first side of the piezoelectricmaterial 3701 (e.g., top side illustrated in FIG. 37G) and a pluralityof lower electrodes 3730 disposed on a second side of piezoelectricmaterial 3701 (e.g., bottom side illustrated in FIG. 37G). In thepixelated arrangement of FIG. 37G, adjacent upper electrodes 3728 can beseparated from one another by one or more gaps 3770A and adjacent lowerelectrodes 3730 can also be separated from one another by gaps 3770A. Aconnection can be made to touch and/or force circuitry via a flexcircuit (which can be bonded to transducer 3700G by an adhesive (e.g.,epoxy).

FIG. 37H illustrates another exemplary pixelated transducer 3700Haccording to examples of the disclosure. Pixelated transducer 3700H cancorrespond to pixelated transducer 3700G implemented with pixelatedelectrodes on one side and a single continuous electrode on the secondside. For example, transducer 3700H can include a plurality of upperelectrodes 3732 disposed on a first side of piezoelectric material 3701(e.g., top side illustrated in FIG. 37H) and a lower electrode 3734disposed on a second side of piezoelectric material 3701 (e.g., bottomside illustrated in FIG. 37H). Adjacent upper electrodes 3732 can beseparated from one another by gaps 3770A. It should be understood thatalthough pixelated transducer 3700H is illustrated with pixelated upperelectrodes 3732 and a single lower electrode, a pixelated transducer cansimilarly be implemented with a single continuous upper electrode andpixelated lower electrodes.

FIG. 37I illustrates another exemplary pixelated transducer 3700Iaccording to some examples of the disclosure. Pixelated transducer 3700Ican correspond to pixelated transducer 3700H implemented such that thelower electrode wraps around piezoelectric material 3701 by way of aninsulating material 3703 to a first side (e.g., top side) from a secondside (e.g., bottom side). In some examples, insulating material 3703 canbe omitted and the lower electrode can wrap piezoelectric material 3701.For example, transducer 3700I can include a plurality of upperelectrodes 3736 disposed on a first side of the transducer 3700I (e.g.,top side illustrated in FIG. 37I) and a lower electrode 3738 disposed ona second side of the transducer 3700I (e.g., bottom side illustrated inFIG. 37I). In the pixelated arrangement of FIG. 37I, the upperelectrodes 3736 can be separated from one another by gaps 3770A. In someexamples, the lower electrode 3738 can wrap around from the second side(e.g., bottom side) of the transducer 3700I to the first side (e.g., topside) of the transducer 3700I by way of insulating material 3703. Insome examples, a via through the insulating material 3703 can be usedinstead of the wraparound. Using an insulating material for thewraparound (or via) connection can result in improved stimulation andsensing of the transducer as described above. The lower electrode 3738wrapping around pixelated transducer 3700I (e.g., wrapping around theinsulating material 3703) can leave a gap 3770B between the lowerelectrode 3738 and one of the upper electrodes 3738, for example.Wrapping around the lower electrode 3738 from the second side of thepixelated transducer 3700I to the first side of the transducer 3700I canallow for simplified connections between the transducer and a touchand/or force sensing circuit (e.g., via flex circuit, interposer, directbonding, etc.). It should be understood that pixelated transducer 3700Ican instead be implemented with a single continuous upper electrodewrapping around from a first side of piezoelectric material 3701 to asecond side of piezoelectric material 3701 and pixelated lowerelectrodes.

FIG. 37J illustrates another exemplary pixelated transducer 3700Jaccording to examples of the disclosure. For example, transducer 3700Jcan include a first upper electrode 3740 and a second upper electrode3742 disposed on a first side of piezoelectric material 3701 (e.g., topside as illustrated in FIG. 37J) and a lower electrode 3744 disposed ona second side of piezoelectric material 3701 (e.g., bottom side asillustrated in FIG. 37J). The first upper electrode 3740 and the secondplurality of upper electrode 3742 can have interlocking shapes separatedfrom one another by gaps 3770A, for example.

FIG. 37K illustrates another exemplary pixelated transducer 3700Kaccording to examples of the disclosure. Pixelated transducer 3700K cancorrespond to pixelated transducer 3700J implemented with the lowerelectrode wrapping around from a second side (e.g., bottom side) of thetransducer to a first side (e.g., top side) of the transducer by way ofan insulting material 3703. In some examples, the insulated material3703 can be omitted. Transducer 3700K can include a first upperelectrode 3746 and a second upper electrode 3748 disposed on a firstside of the transducer 3700K (e.g., top side as illustrated in FIG. 37K)and a lower electrode 3750 disposed on a second side of the transducer3700K (e.g., bottom side as illustrated in FIG. 37K). The first upperelectrode 3746 and the second upper electrode 3748 can have interlockingshapes separated by gaps 3770A, for example. In some examples, lowerelectrode 3750 can wrap around from the second side (bottom side) of thetransducer 3700K to the first side (top side) of the transducer 3700K,for example. The lower electrode 3750 wrapping around the transducer3700K (e.g., wrapping around the insulating material 3703) can bedisposed to leave gap 3770B between lower electrode 3750 and upperelectrodes 3746 and 3748. Using an insulating material for thewraparound and/or connection can result in improved stimulation andsensing of the transducer as described above. Wrapping around lowerelectrode 3750 to the first side of the pixelated transducer 3700K fromthe second side of pixelated transducer 3700K can allow for simplifiedconnections between the transducer and a touch and/or force sensingcircuit (e.g., via flex circuit, interposer, direct bonding, etc.) Insome examples, a via through insulating material 3703 can be usedinstead of a wraparound. Although lower electrodes 3744 and 3750 areillustrated as single continuous electrodes in FIGS. 8J and 8K, in someexamples, lower electrodes 3744 and 3750 can be implemented withpixelated electrodes. It should be understood that pixelated transducers3700J and 3700K can be similarly implemented with a single upperelectrode wrapping around to the second side of the transducer from afirst side of the transducer and with two interlocking lower electrodeson the second side of the transducer.

FIG. 37L illustrates another exemplary pixelated transducer 3700Laccording to examples of the disclosure. Pixelated transducer 3700L cancorrespond to pixelated transducer 3700J implemented with one of theupper electrodes and the lower electrode wrapping around to a common,third side of piezoelectric material 3701. In some examples the secondof the upper electrodes can also wrap around to a fourth side ofpiezoelectric material, allowing for side connections to the pixelatedtransducer. For example, transducer 3700 can include a first upperelectrode 3752 and a second upper electrode 3754 disposed on a firstside of piezoelectric material 3701 (e.g., top side as illustrated inFIG. 37L) and a lower electrode 3756 disposed on a second side ofpiezoelectric material 3701 (e.g., bottom side as illustrated in FIG.37L). The first upper electrode 3752 and the second upper electrode 3754can have interlocking shapes separated from each other by gaps 3770A,for example, with the connection between topside portions of therespective upper electrode connected by wrapping to a different side ofpiezoelectric material 3701. For example, the portions of second upperelectrode 3754 on the first side of piezoelectric material 3701 can wraparound and be connected together on a different side of piezoelectricmaterial 3701 (third side). The portions of first upper electrode 3752on the first side of piezoelectric material 3701 can wrap around and beconnected together on a different side of piezoelectric material 3701(fourth side). In some examples, the second upper electrode 3754 and thelower electrode 3756 can wrap from the first side (top side) and secondside (bottom side), respectively, of the piezoelectric material 3701 toa third, common side of the piezoelectric material 3701 (e.g., a frontright side as illustrated in FIG. 37L). In some examples, a portion oflower electrode 3756 and a portion of the second upper electrode 3754wrapping around to the third side of piezoelectric material 3701 can beseparated from one another by gap 3770B. Wrapping the first upperelectrode 3752, second upper electrode 3754 and/or the lower electrode3756 around the piezoelectric material 3701 to the third and/or fourthside of the piezoelectric material 3701 can allow for simplifiedconnections between the transducer and a touch and/or force sensingcircuit (e.g., via flex circuit, interposer, direct bonding, etc.) onthe sides of pixelated transducer 3700L. Although one lower electrode3756 is illustrated in FIG. 37L, in some examples, lower electrode 3756can be implemented with pixelated lower electrodes in a similar manneras the pixelated top electrode in FIG. 37L. Pixelated transducer 3700Lcan also be implemented with wraparounds on an insulating material onone or both sides of the transducer.

FIG. 37M illustrates another exemplary pixelated transducer 3700Maccording to examples of the disclosure. Pixelated transducer 3700M cancorrespond to pixelated transducer 3700H implemented upper electrodesconnected to touch and/or force sensing circuitry by post-processingconnections. For example, pixelated transducer 3700M can include aplurality of upper electrodes 3758 between a first side of piezoelectricmaterial 3701 (e.g., top side as illustrated in FIG. 37M) and a lowerelectrode 3760 disposed on a second side of the piezoelectric material3701 (e.g., bottom side as illustrated in FIG. 37M). In the pixelatedarrangement of FIG. 37M, the upper electrodes 3758 can be separated fromone another by gaps 3770A. Upper electrodes 3758 can be coupled torouting 3772 by way of vias 3774. The upper electrodes 3758 and therouting 3772 can be separated by the insulating material 3703, forexample. The post-processing (metal-insulator) can be performed on thetransducer wafer and then individual pixelated transducers can be cut.The electrodes, vias and metal routings can be patterned usingphotolithography, for example. Connecting the upper electrodes 3762 torouting 3772 can allow for simplified connections between the pixelatedtransducer 3700M and a touch and/or force sensing circuit (e.g., viaflex circuit, interposer, direct bonding, etc.). In some examples, therouting can continue on another surface (e.g., cover glass) before aconnection to the touch and/or force sensing circuit. Although one lowerelectrode 3760 is illustrated, in some examples, lower electrode 3760can be pixelated in a similar manner as upper electrodes 3758.

FIGS. 37N and 37O illustrate exploded views of exemplary pixelatedtransducers 3700N and 37000 according to examples of the disclosure.Pixelated transducer 3700N can correspond to pixelated transducer 3700Himplemented with an insulating material 3703 disposed over the upperelectrodes. Electrodes disposed above the insulating material 3703 canbe capacitively coupled to upper electrodes for driving and sensing thetransducer (e.g., electrodes on a flex circuit can be bonded via anepoxy or other adhesive). Pixelated transducer 80 can correspond to anon-pixelated transducer 314 of FIG. 3C with an insulating material 3703disposed over the upper electrode. Electrodes disposed above theinsulating material 3703 can be capacitively coupled to upper electrodesfor driving and/or sensing the transducer in a localized manner toachieve a pixelated effect (e.g., electrodes on a flex circuit can bebonded via an epoxy or other adhesive). In particular, electrodesdisposed above insulating material 3703 for pixelated transducer 8N canbe capacitively coupled to upper electrodes for driving and sensing, andelectrodes disposed above insulating material 3703 for pixelatedtransducer 80 can be capacitively coupled to upper electrodes for commonmode driving.

Transducer 3700N can include a plurality of upper electrodes 3762disposed on a first side of an insulating material 3703 (e.g., top sideas illustrated in FIG. 37N) and a lower electrode 3764 disposed on asecond side of a piezoelectric material 3701 (e.g., bottom side asillustrated in FIG. 37N). The plurality of upper electrodes 3762 can beseparated from one another by gaps 3770A. Insulating material 3703 canbe disposed on top of the upper electrode layer and multiple electrodes3766 can be disposed on top of the insulating material 3703. Electrodes3766 can, in some examples, correspond in size, shape and relativelocation to upper electrodes 3762. In some examples, the plurality ofupper electrodes 3762 can be driven or sensed via capacitive couplingbetween the upper electrodes 3762 and electrodes 3766. In some examples,electrodes 3766 can be part of a flex circuit to connect the transducerwith a touch and/or force sensing circuit. In some examples,post-processing (metal-insulator) can be performed on the transducerwafer to dispose the insulator and patterned mental electrodes on thepiezoelectric material. The individual transducers can then be cut fromthe wafer. In some examples, in order to enable capacitive coupling viainsulating material 3703, the insulating material can be very thinand/or have large dielectric constant for high-efficiency capacitivecoupling. The electrodes can be patterned using photolithography, forexample. Transducer 3700O can include a single upper electrode 3768rather than pixelated upper electrodes 3762. The single upper electrodes3766 capacitively coupled to the pixelated electrodes 3766 can result incapacitive coupling therebetween for common mode driving of thepixelated transducer 3700O. In some examples, upper electrode 3768 ofFIG. 37O can be removed and electrodes 3766 can be used to drive andsense the transducer using differential driving techniques and spatialdifferential receiving techniques.

Although lower electrode 3764 is illustrated as a single electrode, insome examples, lower electrode 3764 can be pixelated or mimic apixelated electrode on the second side of the transducer in addition orinstead of the electrodes on the first side of the transducer asillustrated in FIGS. 37N and 37O.

The electrodes of transducers described herein (pixelated or not) can,in some examples, correspond to the full area of the side of thepiezoelectric material on which it is disposed (e.g., to maximize theactive area of the transducer). In some examples, the electrodes cancorrespond to less than the full area of the side of the piezoelectricmaterial. The electrodes of the pixelated transducers can be patternedusing photolithography or dicing, for example. The upper electrodes andlower electrodes can have same or different dimensions or pitch, forexample. In some examples, electrodes on the same layer (e.g., the upperelectrode layer or the lower electrode layer) can have varyingdimensions and/or different sized gaps between each other. Likewise, thegaps between adjacent upper electrodes and the gaps between adjacentlower electrodes can have different sizes. The dimensions and pitch ofthe electrodes can be tuned to meet the requirements of spatialdifferential receiving for touch and/or force.

Additionally, it should be understood that although a wraparound usingan insulating material is illustrated in many of the above examples,(e.g., FIGS. 37B, 37D, 37F, etc.), in some examples, electrodes can bebrought from one side of the transducer to another side by a via throughthe insulating material.

Although the pixelated electrodes (and wraparounds) in the aboveillustrations have a generally rectangular shape, the pixelatedelectrode (and wraparounds) are not limited to this shape. FIGS. 37P and37Q illustrate pixelated transducers with different shaped electrodesaccording to examples of the disclosure. Pixelated transducer 3700P ofFIG. 37P can correspond to the pixelated transducer of FIG. 37A, forexample, however, implemented with different shaped electrodes. Forexample, upper electrodes 3782 can be partially rectangular like upperelectrodes 3704 in FIG. 37A, but unlike upper electrodes 3704, upperelectrodes 3782 taper and narrow to make space for a wrapped aroundportion of lower electrode 3784. Lower electrode 3784 can similarly bepartially rectangular and also taper before wrapping around. Adjacentupper electrodes 3782 can be separated from one another by 3770A.Adjacent lower electrodes 3784 can be separated from one another by3770A. Upper electrodes 3782 and corresponding lower electrodes 3784 canbe separated from each other by gaps 3770B. Pixelated transducer 3700Qof FIG. 37Q can correspond to the pixelated transducer of FIG. 37A, forexample, however, implemented with different shaped electrodes. Forexample, upper electrodes 3786 can be partially rectangular like upperelectrodes 3704 in FIG. 37A, but unlike upper electrodes 3704, upperelectrodes 3782 can narrow to make space for a wrapped around portion oflower electrode 3788. Lower electrode 3788 can similarly be partiallyrectangular and also can narrow before wrapping around. Adjacent upperelectrodes 3786 can be separated from one another by 3770A. Adjacentlower electrodes 3788 can be separated from one another by 3770A. Upperelectrodes 3786 and corresponding lower electrodes 3786 can be separatedfrom each other by gaps 3770B.

It should be understood the pixelated transducers 3700A-Q are exemplaryand other configurations are possible.

It should further be understood that different pixel groupings,electrode pitches, and spatial frequencies (and frequency ratios) thanthe examples explicitly described throughout the disclosure above can beused without departing from the scope of the present disclosure.

In some exemplary configurations such as general differential receiving,without spatial differential receiving, a transducer can be implementedwithout pixelated electrodes. For example, FIG. 3C illustrates atransducer without pixelated electrodes according to examples of thedisclosure. Transducer 314 can include a piezoelectric material 336 witha first electrode 332 on a first side of piezoelectric material 336(e.g., top side) and a second electrode 334 on a second side ofpiezoelectric material 336 (e.g., bottom side). The first electrode 332and second electrode 334 can be stimulated (e.g., differentially) totransmit ultrasonic waves and can be sensed to receive ultrasonic wavesfor touch and/or force sensing as described herein. In contrast, spatialdifferential sensing can require at least pixelated electrodes on atleast one side of the transducer. In particular, spatial differentialsensing can allow for different receiving configurations (e.g., sensingdifferent pixelated electrode or electrode groups) tuned to receiveultrasonic signal contributions tuned to touch reflections and or forcereflections. Thus, the tuning of spatial differential receiving canallow for differentiating of touch and force reflections whenoverlapping with one another and/or improve detection of touch and/orforce reflections even when the touch and force reflections do notoverlap.

Therefore, according to the above, some examples of the disclosure aredirected to an acoustic touch sensing system, comprising: a transducer;a differential electrode configuration coupled to the transducer; and anamplifier coupled to at least one electrode of the differentialelectrode configuration, wherein the differential electrodeconfiguration is configured to reject a spatial common mode signal.Additionally or alternatively to one or more of the examples disclosedabove, in some examples, the differential electrode configuration isconfigured with an alternating pattern of electrodes. Additionally oralternatively to one or more of the examples disclosed above, in someexamples, the alternating pattern of electrodes has a pitchcorresponding to a first spatial frequency. Additionally oralternatively to one or more of the examples disclosed above, in someexamples, the switching circuitry is further configured to: group two ormore electrodes of the differential electrode configuration in a firstgrouping configuration having a first pitch; and group two or moreelectrodes of the differential electrode configuration in a secondgrouping configuration having a second pitch, different from the firstpitch. Additionally or alternatively to one or more of the examplesdisclosed above, in some examples, the switching circuitry is furtherconfigured to: group four or more electrodes of the differentialelectrode configuration in a first grouping configuration having a firstpitch and a first spatial phase; and group the four or more electrodesof the differential electrode configuration in a second groupingconfiguration having the first pitch and a second spatial phase,different from the first spatial phase. Additionally or alternatively toone or more of the examples disclosed above, in some examples, theswitching circuitry is further configured to: group the four or moreelectrodes of the differential electrode configuration in a thirdgrouping configuration having a second pitch, different from the firstpitch. Additionally or alternatively to one or more of the examplesdisclosed above, in some examples, the first pitch corresponds to afirst spatial frequency, and the second pitch corresponds to a secondspatial frequency, different from the first spatial frequency.

Some examples of the disclosure are directed to a method comprising:transmitting an acoustic wave from a transducer; receiving a reflectedacoustic wave at two electrodes arranged in a differentialconfiguration; and compensating for a spatial common mode signal usingthe received signal from the differential electrode configuration.Additionally or alternatively to one or more of the examples disclosedabove, in some examples, the differential electrode configuration isconfigured with an alternating pattern of electrodes. Additionally oralternatively to one or more of the examples disclosed above, in someexamples, the alternating pattern of electrodes has a pitchcorresponding to a first spatial frequency. Additionally oralternatively to one or more of the examples disclosed above, in someexamples, the method further comprises: grouping two or more electrodesof the differential electrode configuration in a first groupingconfiguration having a first pitch; and grouping two or more electrodesof the differential electrode configuration in a second groupingconfiguration having a second pitch, different from the first pitch.Additionally or alternatively to one or more of the examples disclosedabove, in some examples, the method further comprises: grouping four ormore electrodes of the differential electrode configuration in a firstgrouping configuration having a first pitch and a first spatial phase;and grouping four or more electrodes of the differential electrodeconfiguration in a second grouping configuration having the first pitchand a second spatial phase, different from the first spatial phase.

Some examples of the disclosure are directed to a non-transitorycomputer-readable storage medium having stored therein instructions,which when executed by a processor cause the processor to perform amethod comprising: transmitting an acoustic wave from a transducer;receiving a reflected acoustic wave at two electrodes arranged in adifferential configuration; and compensating for a spatial common modesignal using the received signal from the differential electrodeconfiguration. Additionally or alternatively to one or more of theexamples disclosed above, in some examples, the differential electrodeconfiguration is configured with an alternating pattern of electrodes.Additionally or alternatively to one or more of the examples disclosedabove, in some examples, the alternating pattern of electrodes has apitch corresponding to a first spatial frequency. Additionally oralternatively to one or more of the examples disclosed above, in someexamples, the method further comprises: grouping two or more electrodesof the differential electrode configuration in a first groupingconfiguration having a first pitch; and grouping two or more electrodesof the differential electrode configuration in a second groupingconfiguration having a second pitch, different from the first pitch.Additionally or alternatively to one or more of the examples disclosedabove, in some examples, the method further comprises: grouping four ormore electrodes of the differential electrode configuration in a firstgrouping configuration having a first pitch and a first spatial phase;and grouping four or more electrodes of the differential electrodeconfiguration in a second grouping configuration having the first pitchand a second spatial phase, different from the first spatial phase.

Some examples of the disclosure are directed to An acoustic touchsensing system, comprising: a transducer, a differential electrodeconfiguration coupled to the transducer; switching circuitry configuredto: couple the differential electrode configuration to drive circuitryconfigured to drive the transducer to produce an acoustic wave during adrive phase; and couple the differential electrode configuration tosense circuitry configured to receive electrical signals from thetransducer during a sensing phase; and an amplifier coupled to at leasttwo electrode of the differential electrode configuration, wherein thedifferential electrode configuration is configured to reject a spatialcommon mode signal. Additionally or alternatively to one or more of theexamples disclosed above, in some examples, the acoustic touch sensingsystem further comprises: a first electrode and a second electrode aredisposed on a first side of the transducer; and a third electrode isdisposed on the second side of the transducer; wherein: the firstelectrode are coupled together during the drive mode; and the firstelectrode and the second electrode are coupled differentially to thesense circuitry during the sensing mode. Additionally or alternativelyto one or more of the examples disclosed above, in some examples, thethird electrode is grounded during the sensing mode and the thirdelectrode is differentially driven with the coupled first and secondelectrode in the driving mode. Additionally or alternatively to one ormore of the examples disclosed above, in some examples, the thirdelectrode is floating during the sensing mode and the third electrode isdifferentially driven with the coupled first and second electrode in thedriving mode.

Some examples of the disclosure are directed to a method comprising:coupling a differential electrode configuration to drive circuitryconfigured to drive a transducer to produce an acoustic wave during adrive phase and coupling the differential electrode configuration tosense circuitry configured to receive electrical signals from thetransducer during a sensing phase, wherein the differential electrodeconfiguration is coupled to the transducer and configured to reject aspatial common mode signal from a received acoustic wave. Additionallyor alternatively to one or more of the examples disclosed above, in someexamples, the sensing phase comprises a touch sensing phase and a forcesensing phase. Additionally or alternatively to one or more of theexamples disclosed above, in some examples, the touch sensing phasecomprises an in-phase touch sensing phase and a quadrature touch sensingphase, wherein coupling the differential electrode configuration to thesense circuitry during the in-phase touch sensing phase comprisescoupling the differential electrode configuration to the sense circuitryin a first electrode grouping and coupling the differential electrodeconfiguration to the sense circuitry during the quadrature touch sensingphase comprises coupling the differential electrode configuration to thesense circuitry in a second electrode grouping, different from the firstelectrode grouping. Additionally or alternatively to one or more of theexamples disclosed above, in some examples, the sensing phase comprisesconcurrently capturing an in-phase touch measurement, a quadrature touchmeasurement, and a force measurement. Additionally or alternatively toone or more of the examples disclosed above, in some examples,concurrently capturing comprises, concurrently receiving at least foursignals from at least four of the differential electrodes at foursensing circuits and concurrently combining the at least fourdifferential signals in different combinations to produce the in-phasetouch measurement, quadrature touch measurement, and force measurement.

Some examples of the disclosure are directed to a non-transitorycomputer-readable storage medium having stored therein instructions,which when executed by a processor cause the processor to perform amethod comprising: coupling a differential electrode configuration todrive circuitry configured to drive a transducer to produce an acousticwave during a drive phase and coupling the differential electrodeconfiguration to sense circuitry configured to receive electricalsignals from the transducer during a sensing phase, wherein thedifferential electrode configuration is coupled to the transducer andconfigured to reject a spatial common mode signal from a receivedacoustic wave. Additionally or alternatively to one or more of theexamples disclosed above, in some examples, the sensing phase comprisesa touch sensing phase and a force sensing phase. Additionally oralternatively to one or more of the examples disclosed above, in someexamples, the touch sensing phase comprises an in-phase touch sensingphase and a quadrature touch sensing phase, wherein coupling thedifferential electrode configuration to the sense circuitry during thein-phase touch sensing phase comprises coupling the differentialelectrode configuration to the sense circuitry in a first electrodegrouping and coupling the differential electrode configuration to thesense circuitry during the quadrature touch sensing phase comprisescoupling the differential electrode configuration to the sense circuitryin a second electrode grouping, different from the first electrodegrouping. Additionally or alternatively to one or more of the examplesdisclosed above, in some examples, the sensing phase comprisesconcurrently capturing an in-phase touch measurement, a quadrature touchmeasurement, and a force measurement. Additionally or alternatively toone or more of the examples disclosed above, in some examples,concurrently capturing comprises, concurrently receiving at least foursignals from at least four of the differential electrodes at foursensing circuits and concurrently combining the at least fourdifferential signals in different combinations to produce the in-phasetouch measurement, quadrature touch measurement, and force measurement.

Although examples of this disclosure have been fully described withreference to the accompanying drawings, it is to be noted that variouschanges and modifications will become apparent to those skilled in theart. Such changes and modifications are to be understood as beingincluded within the scope of examples of this disclosure as defined bythe appended claims.

1-20. (canceled)
 21. A sensing system comprising: a transducercomprising: a piezoelectric material including a first side and a secondside, the second side opposite the first side; a plurality of firstelectrodes disposed on the first side of the piezoelectric material; oneor more second electrodes disposed on the second side of thepiezoelectric material; and sensing circuitry coupled to the transducerand configured to perform a differential measurement of the plurality offirst electrodes to sense a touch signal at one or more spatialmodulation frequencies corresponding to a differential electrodeconfiguration of sensing the plurality of first electrodes and reject aspatial common mode signal having a common spatial characteristicrelative to the differential electrode configuration of sensing theplurality of first electrodes.
 22. The sensing system of claim 21,wherein: the one or more second electrodes wrap around from the secondside of the piezoelectric material to the first side of thepiezoelectric material; and the one or more second electrodes wrappedaround to the first side of the piezoelectric material are separatedfrom the first electrodes on the first side of the piezoelectricmaterial by one or more gaps.
 23. The sensing system of claim 21,further comprising: an insulating material disposed on a third side ofthe piezoelectric material, the third side of the piezoelectric materialbetween the first side of the piezoelectric material and the second sideof the piezoelectric material; wherein the one or more second electrodeswrap around to a side of the insulating material that is coplanar withthe first side of the piezoelectric material via the insulating materialwithout contacting the third side of the piezoelectric material.
 24. Thesensing system of claim 21, wherein: the piezoelectric material furtherincludes a third side between the first side of the piezoelectricmaterial and the second side of the piezoelectric material; theplurality of first electrodes wrap around from the first side of thepiezoelectric material to the third side of the piezoelectric material;the one or more second electrodes wrap around from the second side ofthe piezoelectric material to the third side of the piezoelectricmaterial; and the plurality of first electrodes wrapped around to thethird side of the piezoelectric material and the one or more secondelectrodes wrapped around to the third side of the piezoelectricmaterial are separated by one or more gaps.
 25. The sensing system ofclaim 21, further comprising: an insulating material disposed on a thirdside of the piezoelectric material, the third side of the piezoelectricmaterial between the first side of the piezoelectric material and thesecond side of the piezoelectric material, wherein: the plurality offirst electrodes wrap around from the first side of the piezoelectricmaterial to the insulating material; the one or more second electrodeswrap around from the second side of the piezoelectric material to theinsulating material; and the plurality of first electrodes wrappedaround to the insulating material and the second one or more secondelectrodes wrapped around to the insulating material are separated byone or more gaps.
 26. The sensing system of claim 21, wherein: thepiezoelectric material further includes a third side between the firstside of the piezoelectric material and the second side of thepiezoelectric material and a fourth side between the first side of thepiezoelectric material and the second side of the piezoelectricmaterial, the third side opposite the fourth side; the plurality offirst electrodes wrap around from the first side of the piezoelectricmaterial to the third side of the piezoelectric material; and the one ormore second electrodes wrap around from the second side of thepiezoelectric material to the fourth side of the piezoelectric material.27. The sensing system of claim 21, further comprising: a firstinsulating material disposed on a third side of the piezoelectricmaterial, the third side of the piezoelectric material between the firstside of the piezoelectric material and the second side of thepiezoelectric material; and a second insulating material disposed on afourth side of the piezoelectric material, the fourth side of thepiezoelectric material between the first side of the piezoelectricmaterial and the second side of the piezoelectric material and oppositethe third side of the piezoelectric material, wherein: the plurality offirst electrodes wrap around from the first side of the piezoelectricmaterial to the first insulating material, and the one or more secondelectrodes wrap around from the second side of the piezoelectricmaterial to the second insulating material.
 28. The sensing system ofclaim 21, wherein: the plurality of first electrodes are separated fromone another by a plurality of first gaps; and the one or more secondelectrodes comprise a plurality of second electrodes separated from oneanother by a plurality of second gaps.
 29. The sensing system of claim21, wherein: the plurality of first electrodes are separated from oneanother by a plurality of first gaps, and the one or more secondelectrodes consists of one second electrode.
 30. The sensing system ofclaim 29, further comprising: an insulating material disposed on a thirdside of the piezoelectric material, the third side of the piezoelectricmaterial between the first side of the piezoelectric material and thesecond side of the piezoelectric material, wherein: the one secondelectrode wraps around to a side of the insulating material that iscoplanar with the first side of the piezoelectric material via theinsulating material without contacting the third side of thepiezoelectric material.
 31. The sensing system of claim 21, wherein theplurality of first electrodes consists of two interlocking firstelectrodes separated by a gap.
 32. The sensing system of claim 31,further comprising: an insulating material disposed on a third side ofthe piezoelectric material, the third side of the piezoelectric materialbetween the first side of the piezoelectric material and the second sideof the piezoelectric material, wherein: the one or more secondelectrodes consists of one second electrode; and the one secondelectrode wraps around to a side of the insulating material that iscoplanar with the first side of the piezoelectric material via theinsulating material without contacting the third side of thepiezoelectric material.
 33. The sensing system of claim 31, wherein: thepiezoelectric material includes a third side between the first side ofthe piezoelectric material and the second side of the piezoelectricmaterial and a fourth side between the first side of the piezoelectricmaterial and the second side of the piezoelectric material, the thirdside of the piezoelectric material opposite the fourth side of thepiezoelectric material; the plurality of first electrodes consists oftwo first electrodes, one of the two first electrodes comprising aplurality of first conductive segments wrapping around to andelectrically connected on the third side of the piezoelectric materialand the other of the two first electrodes comprising a plurality ofsecond conductive segments wrapping around to and electrically connectedon the fourth side of the piezoelectric material; and the one or moresecond electrodes wrap around the piezoelectric material from the secondside of the piezoelectric material to the third side of thepiezoelectric material.
 34. The sensing system of claim 21, furthercomprising: an insulating material, wherein the plurality of firstelectrodes are disposed between the piezoelectric material and theinsulating material; and one or more conductive routings disposed on theinsulating material and coupled to the plurality of first electrodes byone or more vias through the insulating material.
 35. A sensing systemcomprising: a transducer comprising: a piezoelectric material includinga first side and a second side, the second side opposite the first side;one or more first electrodes disposed on the first side of thepiezoelectric material; one or more second electrodes disposed on thesecond side of the piezoelectric material; an insulating material layerdisposed on the first side of the piezoelectric material and over theone or more first electrodes; and a plurality of third electrodesdisposed on the insulating material such that the insulating materialacts as a dielectric between the plurality of third electrodes and theone or more first electrodes, wherein the one or more first electrodesare capacitively coupled to the plurality of third electrodes.
 36. Thesensing system of claim 35, wherein the one or more first electrodesconsists of one first electrode.
 37. The sensing system of claim 35,wherein the one or more second electrodes consists of one secondelectrode.
 38. An ultrasonic transducer configured for simultaneoustouch and force sensing, the transducer comprising: a piezoelectricmaterial including a first side and a second side, the second sideopposite the first side, a plurality of first electrodes disposed on thefirst side of the piezoelectric material; and one or more secondelectrodes disposed on the second side of the piezoelectric material,wherein the plurality of first electrodes and the one or more secondelectrodes are operatively coupled to a processor, the processorconfigured to: receive one or more signals form the plurality of firstelectrodes and the one or more second electrodes; determine a locationof a touch based on one or more received signals; and determine anapplied force based on the one or more received signals.
 39. Theultrasonic transducer of claim 38, wherein the one or more secondelectrodes consist of one second electrode.
 40. The ultrasonictransducer of claim 38, wherein: the one or more second electrodes wraparound from the second side of the piezoelectric material to the firstside of the piezoelectric material; and the processor is electricallycoupled to the plurality of first electrodes and the one or more. secondelectrodes via connections on the first side of the piezoelectricmaterial.